The Virgin Heroine has always been (and remains, IMO) a staple of genre romance. It’s getting not so much that way anymore, but as time goes on and society gets freer with its sexcapades, it’s harder for a writer to justify the Virgin Heroine, especially beyond, say, college age. On the other hand, we still have historical writers who are perfectly capable of pulling off the “wicked virgin widow trope,” which I have to admit is cracktastic and I never ever get tired of it. (Kind of like “I had to do it to fulfill the will” plots, but that’s another post.)
I don’t believe I’ve ever read a contemporary romance (other than an inspirational or sweet) that used religious beliefs as a solid, if not defiant, reason for the heroine’s virginity. And in any case, religious or not, if the heroine does lose her virginity before she marries the hero, she still marries (or commits to) the hero, so it’s all good.