Come on Rasco, you can do better than that!
Seto was thinking that Izumi is going to start trying to snag him (or do stuff like the lets play twister because it's somewhat erotic) And as easy as misunderstandings happen between him and Iori, it could cause problems.
Iori is working a lot, but them making time to see each other, if only for a few minutes, is great. Iori is in a strange place, she really wasn't ready to be in a big production, she has to work hard, has plenty of stress, and is feeling like she is a failure. She isn't even entirely sure that she wants to be an actress if what she's been experiencing is what it means to be an actress.
On top of that, her agency has probably been a pain, not to mention dealing with increasing popularity. She isn't busy all the time because of rehearsal, a large part is probably stupid talent agency crap that they're having her do. Their goals and hers don't match, and they want her to be single because she's more attractive that way... so she probably gets pressure from them.
But it seems like Seto and Iori don't talk enough about work, she still doesn't really confide in him, and he really doesn't have an interest in acting. That actor at the end, giving her encouragement... probably means a lot to her, especially if he's an older successful actor.
She is a good girl, and probably won't betray Seto, or really fall in love with the actor guy, but they could become close friends. The actor might even fall for her, and become Seto's rival and try to break them up... Seto might become jealous of this actor guy who gets to spend way more time with Iori than he does.
I think Izumi was thrown in as a wild card, she probably won't be a real threat to the relationship. But his neighbour, Aso, probably is a big threat. They'll probably become better and better friends/neighbors as time goes on which seems safe because she has a BF. Good chance something happens though, long distance, or whatever, and her boyfriend leaves her. (better for plot purposes, but she could break up with him.) and Seto, being kind, will likely end up comforting her. And... she falls for him. And he might even get confused, because Iori is getting busier and busier as the play opening approaches, not to mention the actor dude... and Aso is right there... Plus he seems to like her already, at least as a friend, so...
It looks like some interesting stuff will happen.