anal penetration yourself or having someone else do it?

[Imconfused]

When I bring the subject up he usually denies anything.
When the times we do have sex and I am going down on him. Just to see what he will do I put my hand around his ass. Most of the time he moves his ass to where my hand would be at his crack. Is he trying to tell me he wants that?
Why can't he just come out and say it if he does? If I am willing to do it, then he should just be honest right?
I know I am only going to get guesses, but talking to other people who like what he likes well, it does help.
I do know an ass doesn't stretch out on its own though, so something is going in and out of it.....