#so even before I'd read good omens I had a notion of this particular point of discussion

[lunaamatista]

There seems to be a fair amount of confusion over what this means in the notes, so I wanted to give my two cents. Most of this comes from the answers linked in the helpful FAQ linked over in Mr. Gaiman’s Tumblr, but I’ll still quote relevant parts of posts or external sources whether they are included in there or not. I’m only including the questions, in bold, when the quoted parts would not be understood without them.

To the statements saying that Aziraphale and Crowley were “intended to be canon back in the 90s” and “planned as in love since the ‘90s,” we’ve received quite the clear answer on this before:

I don’t think of Good Omens the novel as a love story – we were making it up as we went along. [x]

However, the TV show is. 

I definitely planned Good Omens the series as a love story. [x]

We do also know why this is the case:

I think that the TV series leans in more to Aziraphale and Crowley and away from Adam and the Them, but that has more to do with the nature of TV and Adam and the Them not turning up for eleven years after the story begins. [x]

I needed to make Crowley and Aziraphale the stars, which meant they needed more of a plot than they had in the book. [x]

Mostly because the show needed focus, and because it solved the narrative problems of neither of them being in episode 3. [x]

It gave me a shape to Crowley and Aziraphale and let them be the stars of the show. But it also made it all much easier to get to the plot that Terry and I had talked about for the second book. [x]

It should go without saying that they are in love in the TV series, but what about the book? We do have an answer for that, as well:

I have, for the last thirty years, believed firmly that anything anybody wants to bring to their Aziraphale and Crowley [...] headcanon is good with me. [...] As far as I’m concerned, what’s on the page or on the screen is the Only Truth, and anything imagined beyond that is headcanon, so at best I’d just be telling you what I (half a book author, whole TV series author) happen to think. [x]

I understand that could feel non-conclusive, but I’ll give some of my personal input here. 

Sometimes, stories and characters have a life of their own, outside of what the authors intented. This is rather known a phenomenon: 

Many fiction writers say that their characters seem to have minds of their own. [...]  This feeling, the “illusion of independent agency,” is quite common. [...]  Marjorie Taylor surveyed 50 fiction authors and found that a full 92 percent of them experienced this phenomenon of their characters having their own agency. [...]  Mary Watkins has documented evidence of many famous authors who insist that their characters are autonomous and out of their control. [x]

(This, I might add, rings true for my experience while I was sole editor in a literary circle for three years of my time as a Literature student, and for my experience having worked as an editor for half a decade after that).

While I cannot say for certain whether Neil Gaiman (or Terry Pratchett) believes that this is the case for these particular characters, I don’t particularly feel it’s too far-fetched to think so—do note the discussion of the characters as if they were “old friends” with some autonomy, rather than characters who only exist as the words they put to the page:

Terry Pratchett and I were talking about Crowley and Aziraphale over dinner the other night and wondering what they'd been up to ("...on the South Downs? You really think so?"). It was very pleasant, honestly, like catching up with news of old friends. [x] 

It’s not that they didn’t know what their relationship could have looked like to other people in the book itself, and when the only point of reference was the book...

Q. I had read it as Anathema thinking that she had, in fact, just been run over by a very campy gay couple, and a campy gay couple wouldn't harm her. But my mum read this as Anathema, who she thought could feel that Crowley was a demon, realizing that she was also in the presence of an angel, and an angel wouldn't harm her. A. The version that Terry and I had in mind when we wrote it was the former. [...]  She thinks they’re gay. And she was safe. [x]

(In regards to Fandom making a Good Omens primer post back in 2019, when the first season aired). This is so lovely. And inspiring. And an honour. Thank you, Tumblr folk. I think my only correction of any kind would be that people have been shipping Crowley and Aziraphale since the Book was published in 1990. [x]

...but if I had to guess, going back to that very first quote that “we were making it up as we went along,” Gaiman could possibly not want to attribute intentionality to an element of a book whose creation is recounted as being fairly unplanned (I’d expect a lot of people involved in fandoms would be aware of how tiring it is to fans for authors to retroactively make these claims), and especially not a book co-written by someone who is no longer around to weigh on this himself, a sentiment we do arguably have at least a notion of: 

I'm not going to change what's in the book [...] without consulation with my co-author. [x] 

Lastly, a story can have characters in love without being a love story, as the latter is generally understood to be a narrative about a love affair or a tale of characters’ love. Like with many other parts of literature, there is no strict guideline on the beats a love story needs to include, but there are infinite resources on structuring one and, other than directly calling it a love story, Gaiman has explicitly said it is written with the beats of one: 

I wrote the TV series with the beats of a love story. [x]

I'm sad you didn't perceive Aziraphale and Crowley's relationship as a love story that begins on a wall in Eden and which we leave in the Ritz to "A Nightingale Sang in Berkeley Square". It may make you feel better if I assure you that lots of people did see the love story there. [x]

PS — I feel I’d be remiss not to mention that some people go as far to make a distinction between a “love story” and a “romance,” with the former not necessarily requiring the happy ending that the latter does. This was a bit of a hot topic of debate in the publishing world in the mid 2010s as, per the Romance Writers of America association, romance had the following elements: 

Two basic elements comprise every romance novel: a central love story and an emotionally satisfying and optimistic ending. A Central Love Story: The main plot centers around individuals falling in love and struggling to make the relationship work. A writer can include as many subplots as he/she wants as long as the love story is the main focus of the novel. An Emotionally Satisfying and Optimistic Ending: In a romance, the lovers who risk and struggle for each other and their relationship are rewarded with emotional justice and unconditional love. [x]

I cannot claim which definition Gaiman subscribes to, but if it is any consolation, we do have the following:

Season 3 is all planned and plotted and, if I get to make it, will take the story and the people in it we care about to a satisfying end. [x]

Q. Please, we need to know everything will be ok. A. Everything will be okay. [x]

Q. You did say everything would be okay, and thankfully we all know a writer would never lie! A. I wouldn’t lie about that, anyway. [x]

Hello!! I have a question about the ending of s2 ep6 (loved the season by the way!!)

What lead you to making Crowley kiss aziraphale? In the past i recall you mentioning that you felt unsure to stray too far from the original material or say anything new about their relationship without Terry Pratchett being here so i wonder what caused you to change your mind? Not complaining, just curious :)

I said I wasn't going to change anything about the nature of their relationship in the first book, and I didn't. I know what Terry and I had planned for the sequel, though.