Did you get a stiffy when he put his hand upon you and you therefore got embarrassed a that your secret fantasies were in danger of being discoverd, perhaps his gaydar works better than yours, so you can either agree to have your own private liasons and lay the ground rules to who is going to be the boy and the other the girl and enjoy romantic rides out together. Otherwise tell him your not homophobic and flattered by his advances but they are mis directed but do not want to loose his friendship.