I was living with my girlfriend of the past 6ish or so years. Over those six years, the following had happened:
1 - She'd gone from 140 to over 200 pounds. I don't mean to sound like a superficial ass, but, obviously this impacts physical attractiveness. While this shouldn't be the #1 thing in any relationship, it is a big part of what attracted me to her. I meanwhile hadn't gained any weight, at all, so this isn't a pot calling the kettle black deal.
2 - We went from having sex multiple times a week to....maybe once every 3 months. She "didn't feel attractive anymore" so she didn't want to have sex, yet she wouldn't exercise or do anything to try and lose the weight. I think its also important to point out not once did I call her fat, belittle her, etc. I still wanted sex, I told her that frequently. Paid lots of attention to her. No dice.
3 - She got exceedingly lazy in other aspects. Dirty dishes would pile up in the sink. (To those who will likely be like "WHY DIDNT YOU JUST WASH THEM!?" well, I did, but at the time I was working and she wasn't, I didn't think it was fair for me to come home from at times 12 hour work days to a filthy apartment and have to work there, too). The last straw was when our apartment was infested with ants and I followed the trail to our empty laundry closet (we didnt have a washer/dryer yet) to find a week's worth of trash simply stuffed in there instead of taken to the dumpster.
We fought and fought and fought and I told her I was breaking up with her, told her to leave, but she wouldn't. The apartment was in both of our names, so she refused to leave, even though I offered to "buy her out" so to speak. She insisted everything was fine, even though I told her daily we weren't together, I wasn't sleeping in the bed with her, rejected her advances, etc. She claims we were still a couple at the time.
Ended up having sex with 2 different girls during this time, one was a drunken one night stand at a party with a former co-worker, and another was a girl from out of state I met on the internet, one of the most BEAUTIFUL girls I've ever met, we hit it off, eventually fell in love long distance, she flew down to see me, we fucked 16 times in 2 days, best sex of my life....then she went home and "broke up with me". Guess I got what I deserved?