I was studying abroad and my fiance had an affair which I found out about 3 months in. There were lots of long teary phone calls where he said it was over with her and he really wanted to make a fresh start with me when I got back. I loved him so I was ready to accept that. Then he said "but can I just go on holiday with her first, because I've booked and paid for it?" 
So I had to dump him, and he was really upset and put out when I wouldn't take him back a few months later 
There was also the casual fling who went abroad for two months. The day he got back I asked if he would come round, he said he couldn't be bothered but I could go over to his if I wanted. As I wasn't that into him, and I thought this signalled he wasn't that into me, I ended it. He was desperately upset and said I was "The One" and had broken his heart!
Oh and the one who I was living with, who announced he was actually still in love with someone he had dated for 2 weeks as a teenager, and wanted to go on a road trip with her. I was very upset and said he should go and see her and tell her how he felt because I couldn't live like that. He said OK, but if she wasn't interested, he would have me as second choice!
You guessed it... I dumped him and he was really shocked and upset
. He went around telling everyone I had dumped him out of the blue because I thought I was better than him. Then on my birthday he gave me a book called "How to meet interesting men"!
Yes, I'm such a bitch, I dumped all of these men. The poor wee lambs.