Schedule a prostate examination, that'll be your backup. Or you could just ask her politely. My brother-in-law is 32 and my sister's 22, so being 10 years older isn't all that bad really. Just give it a try. Or you could be like me and just assume she's a whore and not even deal with it letting each day pass by knowing that you're a jackass for doing such a dumb thing, but when anyone asks you all you can say is "they'll just thinking about dick". Pay or pain.

Edited as Woman read this forum too !