well when the two of you and giting all truchy feely and he gets a hard it doesn't always mean he wants to have sex but it ussually dose. it means that the nervs in the brain that controles his hormones was stimulated. and because of that the muscles in his leggs relax and that causees the hard . so in a way he dose want sex but somtimes he git will get a bonner when his not thinking dirty . like today I got a hard in class and I was working in woodshop. that's not sexual but the nervs were stimulated!
I get boner with a lot of things that are sexual, but that doesn't mean I am wanting sex. It just means what I am doing or read or what ever is a turn on. Now if he is feeling her up then he maybe thinking sex. I usually don't react for sex until she rubs on me and strokes it while my pants are on.
Wow, well. an erection is a physiological reaction to all the kissing and mingling of pheromones. and aside from that any guy is excited to be making out. So to be fair, we usually do react rather enthusiastically when making-out, but that,by no means, has anything to do with what we are thinking in our conscience mind.
So chill. I guess a parrellel example is hardening of the nipples for girls . just because it isn't visible doesn't mean the girl isn't getting turned on