Anyone else experience this situation?

My partner and I recently began having sex and each time we're both very into it and I can tell that he's horny but his downstairs says otherwise.. He always feels soft, so much that I couldn't go on top because I couldn't get it in (so I played it off like I wanted him on top). I know that honesty is key but it's a fairly new relationship and I don't know how to bring up such a sensitive subject to him and I don't want to embarrass him. So basically I need advice on how to have the conversation and also if anyone has experienced this before?