I've had a regular girlfriend for 4 years, we have great sex and I don't miss anything, and yet I have this fetish - it just drives me crazy to be out without underwear - especially in the summer, with a short skirt / dress, etc. - this it turns me on abnormally much. She's not very enthusiastic usually, but sometimes she does, just for fun and most of all to please me. And this fetish has been with me for years now - I don't know if what's going on in my head is completely normal.
1 antonellagrey_ answered
If you do not disturb the others, the boundaries of the normal and the abnormal are determined by the couple. If your girlfriend doesn't like it, you can convince her without forcing her. It's up to you.