Then you have some wild opinions on what is a betrayal…
Desire always leads to actions. When even a kid saw that and said it was an unhealthy thing, it's obvious that Brook tried to flirt with his best friend's beloved each time.
Maybe you don't feel bad when your wife cucks you. But we are different people with different rules. My self-esteem will never allow things like a friend flirting with my wife. First, I would try to talk to my wife in the first place, so it would be clear that she is not betraying me. Then, if my "friend" tried to harass her, it would be over for our friendship.
Anyway, it seems Brook is the worst Straw Hat. He was awful because he was asking to see panties. But there was an excuse, since he could just lose his mind.
But now it seems he was always just a piece of shit.