Women can't expect loyalty from a man they refuse to have sex with

For the second time in my life, I have been in a LTR that the bitch uses sex as a negotiation tactic. It's my fault for allowing it to happen. But anyway, these bitches want commitment and as soon as I give it to them all the power is in their hands. I'm a horny bastard I'll admit, so when these girls know that and they're my only source of pussy, it gives them leverage. I can't even pinpoint the exact time that the table turned in these relationships where they took my balls from me, but it's happened twice. How do I combat this? It just makes me angry that a plate will beg for commitment and an LTR, and as soon as I give it to them, the power is in their hands. It sucks being in a sexless relationship when I'm positive that I could be spinning plates. If you want me to be loyal, you're going to have to have sex with me more than 2-3 times a month. I had more sex as a single man!

Sorry, most of this is a rant. But in all seriousness, why do bitches do this? Why will girls give you they're body all the time when you're just friends with benefits, but as soon as you cuff them they pull back on the sex? Where did I go wrong in these LTR's that ALLOWED them to do such a thing?