@emme987,
What's the big deal? you've been seeing someone for about a month. it's not like that's commitment territory.
You had sex. He doesn't seem to be totally into you.
He's apparently cool with you hanging out with someone else.
You're into him, he's not so much into you.
<shrug>
If the sex is good, go with that while you look for someone to have a relationship with (if that's what you're looking for).