How can you tell if a guy was just thinking with his d**k not his brain?

I got together with this very well knowing that it would either be just a for fun but also thinking he would want something temporary but relatively meaningful. On the first date we didnt have sex but pretty much did everything else and it was fun. Like i said i am prepared for either outcome but would like to see him again whether it be purely sexual or whatever but im not sure what hes thinking. I cant tell if he just hooked up with me because i was available or because he’s actually interested. Thoughts?