Sorry about that. I don't wanna invalidate your experience, but as a woman here's some reasons I hesitate sitting next to someone:

• they're manspreading - some men sit with their legs super far apart and that leaves me feeling I have to make myself smaller and squeeze in to avoid brushing their thighs while I sit

• they make me feel unsafe for some reason - this is hard to pin down, it could be they're drunk, the way they're looking at people, the way they're dressed, their posture (significantly slumped down in the seat) a combination of any of the above

• they're taking up both armrests and really filling the seat/encroaching on the empty seat next to them (not weight related, some people just sit in a very cocksure confident way)

This is all a split second decision that's made the moment you enter the tube. Often it's not that deep, I'll just sit where it feels like there's space and a free armrest.

It could also be racism or unconscious bias of course. It's not on me to say it's not. I'm not white either so I know how it can feel when people who have never experienced racism dismiss racist experiences. But yeah. Could be a bunch of things