Does this mean he liked me while he was in a relationship?

I was friends with a coworker who had a girlfriend who worked with us several months ago. We weren't close but he would speak to me every once in a while. Him and his girlfriend were together all the time including at work and had the same schedules. I worked with him for a little bit (maybe a few weeks) but he transferred jobs and months later (maybe a year) he transferred back. I learned he's single now and I don't know how long ago they broke up. Im sure they broke up shortly after the transfer because she recently gave birth for someone else. It's been two months since he came back and he's made it clear he is into me. I think it’s weird since he was in a relationship when I met him and out of all people he’s showing interest in me.

Does this mean he liked me while he was in a relationship?
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