A quote from Teachings on Love by Thich Nhat Hanh:
When we try to grow flowers, if the flowers do not grow well, we do not blame or argue with them. We blame ourselves for not taking care of them well. Our partner is a flower. If we take care of her well, she will grow beautifully. If we take care of her poorly, she will wither. To help a flower grow well, we must understand her nature. How much water does she need? How much sunshine? We look deeply into ourselves to see our true nature, and we look into the other person to see her nature.
Of course, my partner is a flower who can also care for himself well or poorly. In that sense, it might not make sense for me to take full responsibility for his growing well or withering. But because our lives are so intermingled, often it’s difficult to tell just where one’s influence ends and the other’s begins. In addition, my husband’s well-being is influenced by my own. If I don’t care for myself, eat well, get adequate sleep, my husband suffers as well as I do. It’s like when I wrote about how my husband and I view our individual goals as shared goals or family goals and work toward them accordingly. From this perspective, it seems like a fairly safe option to assume mutual responsibility for one another’s well-being.
It’s a good starting point, at least, loving one another as we love ourselves.