For me it's about trusting myself again first - not others. Self trust means I recognize those red flags earlier and act accordingly. Self trust means I trust that even if I make a "mistake", I trust myself to figure it out and fix it. I will always be there for Me.
With that component in place, it's up to others to prove their trustworthiness through their actions. Either way, I'm listening more intently to my gut tugs and putting far more faith into those than anything. Now that they are healthy and we are on the same team, they don't lie to me. I can trust them.
IMO You have to have a strong relationship with yourself if you want to develop one with another person, no matter what type of relationship it is. You can't give to others what you don't have for yourself - love, trust, respect.