How so? After marriage, it's on! You can have all the sex you want.
I'm gonna take a stab in the dark here... you aren't married. It's MUCH more complicated than that.
Mormons can have healthy sex lives. Many don't, for myriad reasons. But I think many of those issues can frequently be traced back to being told NO for years, and building up unreasonable expectations. Couples sometimes find themselves on completely different pages. But rather than talk about it, they repress it, just like they've been taught to. But men especially can't just go cold turkey, so they find other outlets.