Chinese wedding belief – is it still relevant today?

I’m 27yo Chinese (Chinese free thinker) and have a buddy (Chinese Buddhist) that I’ve known for more than half my life and we are considered close friends (or at least I thought we are). Both of us are holding our wedding to our respective partners in the next couple of months and my buddy said he can’t attend my wedding due to the Chinese belief that you cannot attend any unlucky / lucky events before and after 100 days of your own wedding as it brings bad luck to your marriage (not sure if this is the correct term, I don’t follow much on those Chinese beliefs).

Just wanna know if people nowadays still follow such old traditions/superstitions? My fiancée and I are still going to my buddy’s wedding even though mine is 1 month before his (which is within the 100 days belief thingy) because we don’t think our marriage is based off luck but more of our commitment to the marriage and our partner.

I initially wanted him to be my best man but I guess I won’t need to even ask him that since he said very clearly he will not come to my wedding the moment I told him about my wedding date. I respect his decision but I won’t hide the fact that I’m disappointed that one of my closest buddy of more than a decade chose not to come to my wedding based off a Chinese superstitious belief.

Am I bad friend to feel disappointed in my friend for choosing not to attend one of my most important day of my life? And I’m also confuse if I should still send him a wedding invite as a kind gesture so that he won’t feel like I did not want to invite him, even though he was the one that said he will not be attending my wedding?