Why would a guy settle for cheaters and drug addicts?

Why would a guy "down grade"? I mean I went out with this guy and I am rich I live in the nice part of town and I am socially popular. I don't claim to be the most gorgeous thing on earth, but I am very cute. I have a great personality, I mean I'm not bitchy or mean, I am always a thrill seeker and ready for a great adventure and I have a lot of guy friends. So I went out with this guy who was a little older than me and who was kind of "a loser". Well we went out for almost a year and a half and I thought we were really in love and we were great for each other. Well out of no where this guy dumps me and then a few weeks later wants to get back together then a month later dumps me again. Well now he has been in and out of relationships with single moms and, well the social rejects of society. I'm not trying to be mean but these girls have slept with half our town, they don't have jobs and put no effort into getting jobs, they mooch off the government, they are drug addicts, and they just aren't very attractive and they are mean! I would not put these girls against pit bulls because the poor dogs would probably get killed. And these girls have all cheated on him, and when they do he calls me up crying about it. So I'm not trying to be conceded and say I'm better than these girls but I mean I am nice, I have morals, I'm not a whore or a drug addict. I work at my daddy's law office so I at least have a job, and I actually loved this guy and never cheated on him. So why on earth is he settling for these girls? Thanks for your answers and please no mean answers!