Young woman falls for a young man but can't reveal it due to a monstrous secret

So, there's a certain anime that came out fairly recently that kind of inspired this idea.  It doesn't have to be the exact same concept, mind you, but the idea is very similar.  The basic premise is that a young woman meets a nice young man and falls for him very quickly.  There's just one problem, the woman is actually a monster, and her monster form comes out every single time she feels overwhelmingly positive, adding some major conflict to the relationship.  Naturally, I'd play the man and my partner would play the monster woman.

I have a few ideas for how to go about this.  One is that the woman has gone her whole life up until now blissfully unaware of her monster form as she has never felt this close to anyone before, and just simply falling for someone for the first time was the big thing that truly brought it out, and at first, she's not even aware of the fact that she transformed when it first happens, and when she finds out, it makes her afraid to confront the man again as she does her best to avoid him so he'll never find out she was the monster who terrified him shortly after their first meeting.  The other scenario is similar to the anime that inspired this, basically, there's a whole backstory where she fell for someone as a kid but then noticed that being open about those feelings caused parts of her body to transform, so she decided to close herself off and never get close to anyone ever again, leading to her being more of a recluse who lives with her overprotective mother, so when she meets the male lead, it's when she's going on a grocery run or something along those lines, and it's when she falls in love with the guy that her monster form comes out completely for the first time.  Another scenario is that she comes from a society of these creatures that generally stay away from humankind, but being more of a rebellious spirit, she has decided to leave her home and move into the city, and that's when she meets the man and finds out how difficult it'll be to hide her true form.

The one thing all three scenarios have in common is that through various circumstances, the guy doesn't see the woman transform for the first multiple instances where it happens.  So every time he sees her in her monster form, he just sees a terrifying monster and assumes the worst may have happened to her human form.  It's only overtime that he starts to put two-and-two together. As for what the monster form should be like, it can be whatever you want.  I really have no preference there.

Anyway, as always, something to note about me, my post length isn't always long.  I can write at least one good paragraph per post if that's a requirement of yours, but don't expect huge posts from me all the time.  At the very least, I can easily avoid one-liners.