Male friend is being weird - please help me understand?

My male friend is acting weird and I don’t know what is going on. Please help -
1) I messaged him after a long time being disconnected and asked him if we could talk. He said, “I’m never too busy for you.”
2) we talk and I ask him to help me with a creative project. He agrees and initially was really into it - he sent me tons of feedback and ideas and was very complimentary of my work. He is very complimentary of me in general.
3) anytime I reached out, he made time for me. Several times he sent red heart emojis.
4) we were exchanging emails and he asked to zoom call. On the call, it felt almost like a date, even though I am married and that was not my intention. He asked me if I was done having kids, made a point of telling me he does not want kids and that he is not looking for a serious relationship. It’s not our usual topic of discussion so I kind of just said, yeah, just do you and moved it along. He was also bragging about how he’s doing money wise and making a point of talking about taking care of his parents.
5) after the zoom, we emailed some more, and he called me his lawyer (I am one but I don’t have clients).
6) I sent him a Christmas card with my husband and kids on it with me. He thanked me for the card, but since then, he has hardly responded when I messaged him. We would have conversations and now messages are super short and sort of terse. He still always responds within 3-5 minutes, every single time.
6) he only ever likes my social media pictures have my face or something neutral like my garden or memes in them. He never likes ones with my family in them.
I am a smart person but really stupid with this kind of stuff. What’s your take? A male friend said he likes me and thought he had a chance until the Christmas card and now he’s sulking but still responding because he wants to be “the understudy.”
Male friend is being weird - please help me understand?
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