But the thing is, I don't really want to stop the sex because quite honestly, I like it. lol. Obviously he does, too, but I know he'd stay with me even if I did say I wanted to stop.
Our relationship is based on pure love, not lust. (not to mention the fact that we're engaged. Mom doesn't know that, though. She won't know for about 3 or 4 years.) Mom doesn't believe he'd stay with me. I'm dying to prove her wrong, but that involves sacrifice on my part.
If I actually wanted to test him, I'd have to lie to him, and I don't want to lie to him...
What should I do? Should I test him and prove mom wrong, or just leave it alone?
First of all, why is what your mom said bothering you so much? If it wasn't true, why would you have this huge desire to prove her wrong? Is it possible you are having some teeny tiny doubts?
Your mom is not in your relationship. She does not define how either of you feel, though she has had a lot more experience in this area. It's important for you to do what is right for YOU, not what is right for your mother.
If you are making choices in your relationship based on your mother's input, then it's not a very mature relationship. I understand mothers can drive us crazy (boy, do I!!), but it's time to start realizing that in another few years you'll be on your own.
You'll have to rely on your own good judgement, your common sense, your gut feelings. Why not start doing that now? If you doubt your boyfriend would stay with you without the sex, then stop having sex and see. If you are fully confident he'd stay with you anyway, then keep having sex.
Good luck.