Communication is vital. Without it, there can't be any trust, because then you are just assuming things that may or may not be there. Communication works both ways, though. And it should be about everything, not just when you are feeling down and blue. If living together, financial matters need to be communicated, and not just in general. Wants and needs have to be communicated, not just expected. When one partner does not communicate, the other partner may misinterpret it and THAT is when anger and hurt feelings arise.
I like the secret word/phrase idea. Why was that not mentioned before? Good idea RP! And if a partner is feeling hurt or disappointed, they should be able to talk with their partner and the partner should not get defensive. Then you are ASSUMING, and that is not healthy in a relationship.
Shared goals are very important. But these need to be COMMUNICATED and not just once a year. Talk to your partner about your goals and their goals. Support them in the ways you both can achieve these. Don't just sit there and assume your partner is on the same path or has changed their goals. If you don't ask questions, if you don't communicate, how are you (or they) supposed to know where they are at?
No relationship is perfect. Sometimes issues come up. Some of these issues can come up many times. But if they do, that means there is lack of communication and you BOTH need to sit down, calmly, and clearly find a resolution. "Reacting" to issues in a negative manner will only be the downfall to the relationship. And NOT reacting will have the same effect.
So if you want to keep the relationship alive, maybe it's time to reflect on how you, and not the other person, can better communicate openly and healthily to your partner. Communication, with work, can make a relationship stronger and healthier.