See, his mother already knew. His poorly thought out lie was no match for the intuition of a mother in a romcom.
I like that she was emotionally intelligent enough to understand something was going on, for her son to be cohabiting with a girl who's a stranger to their family, and in the first place, sharp enough to notice something was amiss and went over to investigate. She quickly found out upon going through the house, and in the end she had him completely figured out.
I wonder how much of that conversation did Aoi hear through the door? There wasn't any straight up talk if he loved her, but her mother sounded supportive of the possibility he'd have feelings for her. She was warning him about him ignoring his feelings since he might end up regretting it.
Izumi is right, Aoi is also friends with her and Eiji, and these two aren't going anywhere unlike Akira.
Aoi's face on page 30 says she is at a crossroads, she was feeling antsy and seemed like she was struggling with the idea of whether to say something to him or not, and decided not to.
Yet later she crept into his room, likely regretting her decision to not say anything. To me, it seems she is
very much in love with him now (sneaking into his bed wouldn't happen if she had no feelings for him) and perhaps at that time she wanted to say "don't leave" but knew that's the one thing she couldn't say...
The air is getting thick with romantic tension... I love it, keep going and don't de-escalate on us now.