What Are Your Thoughts About This Ladies!

I've been talking to this one guy for awhile now. When we met his personality was great, we would talk everyday and also hangout. I'm really into this guy. I've been showing my interests into him alot since we met but I've been noticing his interests in me are starting to slow down. It use to be us calling and texting each other and now it's just me doing it. He don't take me out and my birthday was in June and he didn't even wished me a happy birthday. Long story short, We were hanging out one night and having a conversation. He came out and said too me. He wouldn't care if I see other man as long as he doesn't know about it. It's okay with him and as along as we are still having sex with each other he's okay. He doesn't want to know what I'm doing. That's why he doesn't ask me.....What does that mean when a man say that? Is he leaving his option open? Does he want this too be friends with benefits? Does he not want a relationship?......I've never once had a man say those things too me so I definitely need ya'll ladies opinion/thoughts.