I think the most common reason is that they tried to find someone else unsuccessfully and they don't want to be alone
Most Helpful Guy
Because they're fucking stupid and actually think they can reconcile and ride off into the sunset together and live happily ever after. The other ones that get me are the dumb fucks that think they can stay friends
Most Helpful Girl
I dated one guy eight times (since high school off and on). Not gonna lie, that dude is a 15 on a scale of 10 for his skills in bed. More often than not the 3-6 month flings we always had were worth it.