I've definitely used broken trust in my stories and read many others, I'm a sucker for emotional hurt/comfort. But as for amends being made and what causes the loss of trust, I think it is very individual to the character. What might really upset one character would roll off the back of another. It might not be just one thing, but the culmination of things that results in the final loss of the trust. Making amends is also very personal. There's a theory that I think is by the same person who says there are 5 love languages, that there are also 5 apology languages, and depending on your personality, you might want different types of apologies. The five are: expressing regret, accepting responsibility, genuine repent, make restitution, request forgiveness. Some people want only one, some want multiple. I think the key in showing a loss of trust is making sure the reader knows why the character feels that way. Is it because of something that happened in the past and they already feel off kilter and something pushed them over? Did the other person do something they knew the other person would be upset about? Does the character know intellectually the feeling is silly but emotions aren't rational and we feel how we feel? It's almost too broad to talk about in the abstract. Did you have a specific event or type of loss of trust in mind?