I'm 25 and married and have only ever had sex with my DH. Some of my friends think this is weird and one even remarked that she felt sorry for me as I have not had much "variety" 
I didn't think it was sad or weird and im very happy with my DH. Probably just my autism rearing its head but she made a joke about it with another friend in front of me and seemed to brag that she had slept with atleast 10 people and I felt a bit pathetic about only sleeping with one person.
Don't even know why she brought the conversation up but wish she hadnt. I felt embarrassed and our other friend could see how upset I was and said "guess we know who the bike of the group is". This made me laugh.
But really what wrong with only sleeping with one person?