First, let’s address expression versus suppression. Put simply, tell your partner how you are feeling. Holding in stressful emotions can literally manifest itself in physical ailments, so do not avoid or indefinitely postpone anything that needs to be discussed. If you are angry, for example, holding in your feelings today can lead to a potential explosion tomorrow.
Second, recognize the difference between feelings and behavior, and try to focus on your feelings and not your partner’s behavior. For example, if your partner did something which hurt you, tell them about how it made you feel rather than harp on what they did wrong. This approach is far more effective in engaging partners because it helps them become less defensive and listen more to your concerns. Also, be aware that there is a big difference between being assertive and “nagging.” Being assertive means offering a solution. Emphasize that you are coming from a helpful place, and want to work together to create a better union. Nagging, on the other hand, usually involves pointing out “cracks” in your partner and relationship, which has the effect of pushing your partner away.