Does my ex boyfriend want me back?

We broke up and did the whole fwb thing for a couple months until I ended it by sleeping with someone else. He rebounded off of me with this new girl and he's with her now. He recently came back into my life and keeps it a secret from her. We havn't done anything ual, just flirt a lot.. we hang out, we talk entirely too much, and he spent the night on my couch one night. Anything he says about her is never nice... and he's trying to get me to move into his apartment building ( namely the apartment next door to him).. the thing is though, he's still with her even though he says he's unhappy. I'm keeping my distance enough cause I don't want to cause too much trouble.. but do you think he might still like me? What should I do?