Most Helpful Guy
Sounds like he's not willing to settle down. It's all about the sex, about the sex, no trouble.
He could really li k e you but is not willing to give up the other situation. Is the big sign. Send him on his way. If he really likes you he'll find you again.
Most Helpful Girl
Be mad that he went on a date with you but is already seeing someone.
The guy wanted to see if the grass was greener and so went on a date with you. It sounds like you dodged a bullet.