When it comes to relationships, trust is a big thing. The way people seem to think about trust is as if it's something we place in another person. We say "I trust him" or "I don't trust her." This approach implies that trust is about the other person; it's something we give to them if they earn it from us, if they prove themselves to us. It's something that can be broken if the other person behaves in a way we don't approve of or expect. I think there's an even better way of thinking about trust.
What if you thought of trust as something you have in yourself?
For example, trust in your ability to take care of yourself in the context of a relationship. Rather than thinking Can I trust that person? you would think Can I trust myself to take care of myself with that person? If the answer is yes, it leads you to build and grow the relationship. If the answer is no, it leads you to problem solve and then if the answer is still no, then it might be time for you to cease putting energy into that relationship.
This way of thinking of trust calls for you to take care of yourself in relationships. It makes it natural to consider what works for you and what doesn't. It makes it easier to handle behaviors that might make you uncomfortable because you see that you get to choose how to take care of yourself. It shifts the nature of what would otherwise be experienced as breaches of trust; you no longer have to feel "betrayed" even if you don't like what's happening. The way it feels to be in relationships suddenly shifts. Just with a shift in your thinking, you have more power and freedom in relationships. You're free to allow people to be who they are.
You'll come to understand that placing your trust in the other person is placing your power in their hands. Sometimes people do as we expect and that trust is comfortable. If your practice is to place trust IN the other person, then you will most likely seek to maneuver (or manipulate) that person to treat you the way you want to be treated. It's a precarious position in which to put yourself -- it puts your well-being in someone else's hands. It's especially precarious because it leads us to expect others to always do right by us (even when we've neglected to articulate how to do so). When the other person behaves in a way we don't expect and don't like, we react as if that person has done something wrong. Our reaction to breaks in trust vary in depending on the situation; some of us may directly ask for what we need instead, some may try to influence the other person to bring them back into line with our expectation, by using anger or blame or shame or passive aggressive techniques like gossip. Sometimes our efforts work and sometimes they don't.
Even a person who does have your well-being close to their heart is unlikely to always say or do exactly what you want in all instances. When a bad enough breach happens, you experience it as a betrayal and begin to withhold trust. Self-protection is natural. The other person is likely to experience this negativity. A spiral of disconnection begins that can be hard to repair.
Instead of "trusting" someone, think about trusting that person to be who they are. Then trust in your ability to be OK with that person as they are. Your job is to observe and know that person and to develop some understanding of whether you are able to take care of yourself and feel comfortable in the relationship. Just by turning the idea of trust around so that it's not something you place in someone else, but something you keep for yourself, you naturally handle relationships more responsibly. When there is trouble in a relationship, the old way of thinking would've been about how to make the other person change to make you happy; "What does s/he need to do to regain my trust?" Using this new way of thinking about trust leads you to look to yourself first and consider "What can I do for myself that will help me feel better in this relationship?" Do you see how thinking of it in this new way might lead you to new options and better actions? It reminds you to be responsible on your own behalf in relationships, rather than 'trusting' others to be responsible to you on your behalf.