Guess you can only have dumb characters like this in doujinshi huh?
Anyway, my guess for what happens next (if there will be): Hasegawa found out they were having sex (and were actually in the middle of it). Process to beat the NTR-dude up, then ran away with Ichinose. After learning the reason, accept to lose his job, then start to make love with her. She was happy at first, but after everything done realized she couldn't reach climax. Left him, met up with the NTR-dude and has sex non stop. Maybe we will also get a scene where she video call Hasegawa to break up with him while still having sex. The end. Typical NTR slut lol.