[Nanakusa Amane] 16 Sai ni Natta Tsuma 01-14

From the last pages, I think the older Rena actually found Rui's (the other guy) true face and was running away from him for some reason (?). I don't think the 29-year old Rena cheated on Sayama (the protagonist), at most, she was almost starting to get into the early stages of emotional cheating (the guy is charming, after all, and the bar waitress said he was playing with her), but probably nothing really happened. But the 16-year old definitely cheated on him. That's why I really hate dumb bitches. She lost her memory, she went back to the time she loved her now husband. Then some guy just came and said they were lovers and she was instantly ok with him being touchy feely with her. What she should do was to make sure not to do anything crazy before getting her memories back.

Fuck I need a summary. Did she cheat on him then decided to get a divorce?? Then somehow lost part of her memories in an accident??