polyamory

When it rains it pours. I'm sorry that you had a rough time. Breakups do tend to cause some fallout and that's not uncommon.

A good way to insulate yourself is to date outside the polycule whenever possible and avoid dating people's support structures (friends/family). Set some realistic boundaries for yourself. For example, I know sharing multiple partners with the same person is hard for me so I choose not to do that.