Why would my Coworker say this?

I acknowledged my coworker already like 9 years ago when I started and thought always he is very handsome but only like 2 years ago I really started to work with him.
We get along very well and I have the impression he likes me too. However we are both married, each of us having one child.
The other day he told me my opinion is very valid to him, and I’m not talking about business related topic but rather on feedback about personal behaviour.. Two weeks ago he called me and after having talked a bit he asked if I was alright and even though I wasn’t I said yes and he later he called again about something and asked again if I was ok eventough I tried my hardest to sound good he still caught my bad vibes. Anyways now 2 days ago I admitted that he was right and he just said „I know“ and then said that whenever I say something related to him it really hits him and he said that he doesn’t care about any other opinions about his behaviour but when I say something he really valids it and takes it seriously.
Why would he say that? Because I was honest and opened up so he did the same?
I’d really like to know your opinions..
Sorry englisch is not my first language

Why would my Coworker say this?
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