Have you ever left a LTR with a good man?

[whatnowocantfigureout]

Thinking of leaving my 6 years LTR.
We've had our ups and downs as I'm sure many others have, but always got that niggle in my mind I could be happier.

My DP is handsome, caring, emotional, supportive, but I'm just not happy and I can't stop fantasising about other men. Our sex life is non-existent. I do not enjoy it with him.
But yet, I still can't seem to let go. I'm scared to leave incase the grass will not be greener. Good men are hard to find and my friends always remind me of this.
Why can't I just be happy?

Because to be happy you have to have the big pieces of the jigsaw in place and if sex matters to you then that’s a big piece. It matters a lot to me and I couldn’t stay in a relationship where the notion of doing the horizontal tango made me physically recoil. But it is different strokes for different folks - a very close friend has been married for 20 years and they never have sex and it works for both of them - it would drive me up the wall, but for them it is what they both want.

It's a horror show out there OP. Is nothing salvageable?