Why is he doing this?

There's a guy I like, and I can't tell if he likes me.

He is constantly calling me, sometimes even late at night (just two nights ago, he called me at midnight and we were on until two in the morning). We share so much in common, and he opens up to me about things I'm not sure he even talks about with anyone else. However, he keeps bringing up this other girl in my presence and comparing her with me. For example, "(Other girl's name) would react differently to what I just said than you did." Or "Do you know what (other girl's name) told me earlier today?" It's really ticking me off and I have no idea what his intention is behind this. Also, sometimes he'll call me and I'm happy it's just us two talking, and then he asks me to add her into the call and acts way more peppy with her. Is this an attempt to make me jealous?
Why is he doing this?
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