Holding onto yourself, maintaining a relationship with yourself--is not easy.
However, the benefits to you and your marriage are huge. Your ability to hold onto yourself allows you to pull out of negative interactions and conduct yourself in ways that lead to positive ones.
It lets your break the "set" of your communications--habitual topics, patterns, intensity, and tone.
Instead of matching your partner's feelings and emotional tone when you are locked in arguments, bad feelings, or flaring tempers, holding onto yourself allow you to break free of this form of emotional gridlock called "negative affect reciprocity."
Holding onto yourself does not mean "go down" with your partner when he or she becomes depressed, despondent, and hopeless. Often this is interpreted as a lack of caring or empathy. Such as, "If you you understood or cared about me, you would feel as bad as I do!"
But not getting the upset whenever your partner is distraught stabilizies your relationship. Poorly differentiated people can only contain their reactivity by becoming reactive. The ability to "hold on to yourself" permits deep connections with your partner's feelings without break contact or becoming reactive.
Having a sold self that is permeable allows you to takes others into account; there is room for your spouse's reality without loosing your own.
Passionate Marriage - Schnarch