#...on the side of slightly less long-windedness

[mmikmmik]

When Mirabelle chews Siffrin out in Act 5, she actually does correctly touch on a huge issue in their relationship that's prominent from at least Act 3 and arguably present before the loops.

From the ISAT script project (emphasis mine):

Mirabelle: Is something wrong, Siffrin? Did something happen? Did you have a nightmare or something? Siffrin: No, of course not. Mirabelle: Then what happened, Siffrin! Because clearly something did happen!!! Otherwise, i-if nothing happened, I'll have to accept the fact that I was wrong about you!!! Siffrin: (Huh…?) Wrong about me…? Mirabelle: . . . Mirabelle: You always tease me, Siffrin. And it's fine. Everybody does. I guess I have the kind of personality where it's easy to want to tease me. But I know people don't mean it. It's how-- It's how some people make friends. And I thought it was the same for you. I thought, "It's okay, they don't mean it, it's how they are. They tease me, but they're never mean. And Siffrin never really hurts me." "Would never really hurt me." Mirabelle: . . . Mirabelle: But now you have, Siffrin! Thinking I should be alone… Telling me I should be alone… Who do you think you are, to say this to me? Acting like-- Like you know better than me!!! Always soooo mysterious, Siffrin, always talking as if you're better than me! As if you know me!!! But you don't, Siffrin!!! You're just as lost and useless as I am!!! So stop!!! Talking!!! As if you know me!!!!!!

I think it's easy to miss because so much of what Mirabelle says is off base. Because Siffrin insists "no, I really did just decide to suddenly undermine your self-confidence and trust in me out of nowhere for no reason, on the day before we're supposed to fight the King together", Mirabelle goes off that premise and rants that they must never have really cared about her or their mission. Obviously untrue. I think even Mirabelle's dialogue here is hinting that she knows on some level that this is one of her deep insecurities coming to the surface and it makes more sense if something did actually happen that Siffrin is refusing to explain.

But it is true that Siffrin acts superior sometimes. At the start of Act 3, Mirabelle sees him freaking out after his first meeting with Euphrasie and tries to comfort him. She sees through multiple attempts to laugh it off or deflect her (i.e., lie to her); she coaxes them to talk to her, she begs them to talk to her, and finally gently but seriously tells them that the group needs to trust each other and share their worries. And Siffrin's take-away from that last tactic is... "[I] know why she's asking [me] this. Poor Mirabelle can't just say it, so [I]'ll have to do it for her..." and asks Mirabelle what she needs help with, to Mirabelle's visible and uncharacteristic frustration. What condescension! Siffrin was being way nicer about it when he was in a better mental space, but he was basically doing the same thing Mirabelle correctly accuses him of doing in Act 5.

To be fair to Siffrin, they seem genuinely confused in Act 3 when Mira is trying to convince them to share with her, so I think it's more about them being repressed and inexperienced with friendship than an ego thing. But I do think ego is part of it, if only in an "I like myself better when I'm making Mirabelle happy" kind of way. Whatever's going on internally, the bottom line is that Siffrin is not treating Mirabelle respectfully as his adult peer and friend.

Of course Act 5 Mira doesn't remember that Act 3 conversation, so given how she described the behavior, I'm guessing Siffrin has done this sort of thing occasionally before the events of the game. And I think you can see some similar behavior in earlier acts. Siffrin worries a lot about saying things that might have upset or embarrassed Mirabelle, and a lot of their non-plot-related dialogue variations I can think of are trying to be more encouraging towards her. That's more of a grey area, though - I'm not sure I disagree with him doing stuff like faking enthusiasm for the sleepover idea or calling her plant cute. It's kind of a red flag in the context of everything else, but I can't really blame him for it. Even if these issues were fully present before the loops, I think Siffrin and Mirabelle could have worked past them without having to have a really awful fight like that, if Siffrin wasn't falling apart so badly. I really, really like their resolution to be "feelings buddies" as a conclusion to this character arc - yeah! opening up! mutual trust and reassurance! willingness to be vulnerable with each other! Good for them!