Compassion is THE healing energy of life, so it behooves us all to practice it in the place we live every day- our life with our partner. My husband and I adopted a quote from the Dalai Lama as the mission and working principle of our marriage, "Be Kind Whenever Possible. It is ALWAYS possible." Even if you adopted this all by yourself you could transform the energy that lives in the space between yourself and the space you share with your partner. 

Using this as your guideline, you will always know what to do. But remember, we don't have to feel like doing something to do it. We can practice compassion even if our partner is behaving unconsciously and reactively, and not showing any compassion of their own. Practicing compassion is as much about what we don't share as what we do- the little moments of annoyance or irritation, a look, a tone of disapproval - these little things we don’t say can do so much to destroy any good efforts. So, practicing containing criticism of any kind is as important as saying kind and loving things. 

I love what Byron Katie says about relationships, "True love is wanting for your partner what they want for themselves." It really does cultivate a benevolent attitude.

Also, the four critical moments, 1) when we first see each other in the morning, 2) when we say goodbye, 3) when we first see each other at the end of the day, and 4) when we say goodnight - can be clearly defined moments where we practice loving kindness. All of this will lead to a climate of compassion in your relationship, and that is a very good climate indeed!