I'm my opinion, this isn't a porn issue at all but 100% a communication issue. Have you talked about why you're not having sex? Is it because you're busy? I know it sounds super unsexy, but scheduling in time for sex could help you. (Look at it this way: If you know it's coming on a certain day, you can build anticipation!) Is it because she's not having fun? (aka orgasming?) Then learning more about her body and what she needs is really important - but also as an LDS woman she may be struggling with coming into her own sexuality. Is she just a lower desire partner? Then your focus needs to be on helping her want it more... Foreplay, love language stuff, etc. For any of these reasons, I recommend googling Jennifer Finlayson Fife and reading up on how to resolve the disconnect.

When I was married, I was the higher desire partner and I was happy with sex once during the week and once on the weekend.

Definitely don't threaten her with porn. That's a HORRIBLE idea. I'm not sure how open minded either of you are... Sometimes this is all about what you're okay with. Maybe she's okay with you masturbating because it takes some pressure off. You could ask her. Maybe she's not, or maybe she's open to giving you hand jobs instead of sex. What's important is that your sexual experiences are shared, in my opinion.

Bottom line... Communication. You can't solve the problem until you know the cause. And you can't find solutions without open safe spaces for brainstorming.