While general compatability is more easily defined, I find sexual compatability more elusive to describe. Whilst I think that the "good fit" is very much a part of it it can also include things like moral issues, ideas of intimacy and maybe for me the most important issue is how comfortable am I with the person. Libido is also another issue. As someone who has been described as "greedy", there is nothing worse than feeling like you are pressuring your partner for lovemaking sessions. I also think that desire has a big part to play in compatability.

In the words of Outcast....."Sex is always better when there's feelings involved".