Why? Are you attracted to fat women or did she become fat over the years. If it's the latter then I understand the loyalty.
I like some meat on my girls... don't really go for the skeleton models that the fashion industry is forcing down our throats. I do go for the C's and sometimes D's doe. Them training bras don't do it for the Jontro.
Maybe it is about personalities and interests that are compatible. I offer to you the same advice that was offered to me years ago. When finding a spouse, you should find somebody you really enjoy talking to. As years go by, you do a lot more talking and a lot less screwing.
Big girls need love, too. As a fat girl that has only dated thin/fit, relatively attractive men, I might have some insight. Being a decently proportioned fat girl means I have huge boobs and a decent ass and I'm comfortable with my body. Some go for that. Others, I'd imagine, enjoy my personality enough to get beyond what might be seen as physical shortcomings. It may just be that the type I go for are less shallow and more mature. I can't say I've ever dated a chubby chaser, so I don't know what that's like.
I usually see things happening the other way around. How do some of these fat dudes score hot chicks?
Why does it matter as long as they are happy? Are you worried you're missing out on something? It's just a strange thing to catch your curiosity. I guess those guys would have to speak for themselves.
You sound jealous. Not a very good attitude to have about dating; IE the whole "HIM!?" attitude. Some guys just have game and other things going for them than their abs.
I don't think it's strange. You normally expect similar people to be attracted to each other. If you see an old/young couple, tall/short couple, fat/thin couple, pretty/ugly couple, it obviously stands out.
Women are attracted to money and power as well. I would probably put those above looks for most women as they get older.
This is obviously false, because my power is over 9000 and I don't have women falling all over themselves over me.