I'm a happily married guy with many kids and a fantastic wife. We have plentiful sex even after 20 + years of marriage. So why do I get such a thrill when I see another woman's panties peeking out the top of her lo-rise jeans? Why do I have urges to sniff panties belonging to other women?
I don't think I've ever had any serious fetishes in my life, but obviously, you're in good company with this one. If it isn't interfering with your marriage and it isn't causing you serious guilt, enjoy the fact that you still feel sexually alive when you get a peak at a lady's undergarments.