This is a bit of a late reply, but I came across your thread and your BF sounds very much like my ex, down to the best friend.
My ex also had a best friend like Tom. Perpetually single and chasing women, going to nightclubs with my ex, would even flirt with me in front of my ex. All through this, my ex let it happen because he was in awe of his friend and did anything he wanted.
Turns out the problem was my ex, not his friend. He also turned out to be a snake, manipulating and gaslighting me and believing he was doing nothing wrong by flirting with other women, going out to clubs wit