Waiting for your "one true love" to come back to you even though they are involved with someone else and generally unavailable gets romanticized a lot in media, but coming from the object of that unrequited affection, it's pretty creepy.
Yeah, how many times have we seen the male lead wait until the heroine is about to sleep with/move in with/marry the 'other guy' and then come banging on her door? You have to butt in now? You couldn't figure out that you loved me during all the time I was single and available, it has to be now?
The RL problem with that is that so often the guy only realises he wants you when he can't have you, but if you break off your relationship
and go with him you turn from 'idealised fantasy object' to 'ordinary girlfriend' and some guys will go off chasing the next unattainable girl...
Sorry all... this brings me to 'Dear John' (spoilers ahead if you have not seen it)
The guy starts out all noble, rescuing her purse when it fell in the ocean, other corny sappy stuff etc etc, but it doesn't take long for him to develop charming jealousy issues towards all the other male friends in her sphere and start punching more than one of them despite his protestations that he's "changed" from the angry young man who used to tear up beachside bars.
He re-enlists after September 11, which is very noble and heroic, but clearly the girl he left back home is barely a consideration in his decision. But when she sends him a letter telling him she's marrying someone else, he goes off in an extended rage ending up being wounded and shipped home. He meets with the girl, her husband (the friend he punched who was now dying of cancer) and decides to be all noble and walk out on her again.
Also (sidebar) anyone who ran into an airport checkpoint the wrong way through a metal detector a week after 9-11 would have several heavily armed men carting her away, not a kiss from her soldier boyfriend.
Then the girl sends him a letter saying 'hey my husband died, wanna hook up?' and they meet in some coffee shop, the end.
How any of this is supposed to be romantic beats me.