Why is my best freind such a now that he has lost his virginity?

i have been best freinds with this kid for 8 years now and last year he got a gf and they have been dating ever since.. it started out cool, with all of us hanging out together having fun. and about a month ago they had and now she is a complete ***** to me and is his little puppet, she went from having her own views to following him, and he is just a total cynical *** to me, ike i am lesser of a person bc i havent had yet.. why????