How to Lose and Rebuild Trust

I don't condone cheating, but I do know that sometimes there are moments where things can really get wild. It's reflective of other bigger problems in the relationship which can be worked through. Trust needs to be rebuilt because that's what's been chatted. So this person needs to figure out what their needs are to trust that person again. What could that be? Like, how do you lose and then rebuild trust? God, that's a big question.