danas, I'm no master in manifestation in this area, but it seems that my manifestations are much better when I want it without reservation. Maybe there is something unconsciously holding you back? You can ask the universe to show you what is holding you back or what would be the disadvantage of an solid intimate relationship. When you know, you can anticipate or renegotiate your wish.
P.S. How did you manifest great sex? In the past I have thought about employing the LOA for this, but couldn't really figure out how to do it. I'd like to hear your experience/ method.