Well they could have been a relationship that has gone kind of cold but they had good relations with each as like friends. It's like a lot of marriages that goes well and long lasting but die out of love and just leave a husband and wife together because they have good relations with each other
I understand how you can be turned off by the fact that a 10 year relationship ended so easily. Long distance relationships are hard. Sometimes the relationship just becomes different and you both are walking different paths. Saki clearly stated she isn't a clingy person which I'm guess the type of person he wanted. Yeah, they look good together doesn't mean they were meant to be. I am not condoning that he cheated on his long time girlfriend. That was wrong of him.
The second story left a bad aftertaste... a 10 year relationship ended just like that!? He cheats and the girlfriend says ok you can be together!? I mean, it doesn't feel right! o_O'
The other stories were good.