Why my ex started to follow other girls?

I just can’t seem to wrap my mind around it. I (23F) feel lied to and manipulated.

Ex (28M) was afraid to commit at first due to long distance during the week bc of his work which he is really committed to. He finally insisted after 6months and we stayed in a relationship for a month. I've always been pretty chill never bothered him with anything, and he usually messaged me each night after his work but two nights in a row he didn’t, I told him it would be good for us to keep in touch morning and night to feel a certain presence and he straight up told me his head was always at work and that is what he was afraid of, that he knew he couldn’t make me happy the way I wanted and that he didn’t want to make me lose time. I agreed without insisting any further and while remaining cold.
This was 13 days ago. The day after he started to follow new girls on ig to this day who follow him back so I’m pretty sure he’s back on dating apps.

I really don’t know how to feel. He didn’t even fight for our relationship and is already looking for a new one.

Why my ex started to follow other girls?
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