Was he flirting with another girl just to make me jealous?

So I noticed this guy can be really inconsistent with regards to his behaviour.

He was once all 'sit here' (as in next to him) to another girl. A girl who I thought he liked.

My gut feeling is he was trying to make me jealous.

I don't know if he was but he spent most of the time afterwards focusing on me not her. I don't know he seems to act out a lot around me.

Updates
2 mo
I mean I have definitely seen signs he likes her so I didn't know what to make of that 'sit here' part. This guy is so weird I mean if he likes her why would he use her to make me jealous I almost wonder maybe he doesn't like anyone and is playing with both of our feelings.
Was he flirting with another girl just to make me jealous?
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