My girlfriend wears them because they don't show a panty line. She says they are uncomfortable though. When we lounge around she wears normal undies and will actually change out of a thong as soon as she gets home.
You might want to look into why you were into her so much in the first place and also why realizing that she was too much like your mom scared you off.
They are pretty disgusting. I always imagine how brown the part that sits in their ass must be. Boyshorts (NSFW) on the other hand... Holy Mary and Jesus...
On quite a few occasions i've noticed two or more women gossiping about another lady, always shocking how brutal the tear down can be. Even seems to transcend the age barrier as well.