It's a nice story but I can't get over the fact that every previous boyfriend dumped her. Why?? She's beautiful, cheerful, goes all the way, and does whatever the boyfriend wants on dates. She's like a perfect girlfriend, specially in those early youth years. I just can't fathom that anyone would let her go, specially that many guys as the manga seems to imply.
At the very least, it should be that SHE let THEM go when they weren't taking her seriously, or something like that. It would be way more believable than they dumping her on random dates.