Well, first the disclaimer: I don't accept DM, because it's terms are so vague and elastic they can be made to apply to anything.
...which means yes, you could talk about marriage dialectically. It's a fusion of two people into a unit, and the unit's behavior and development is partly the result of the two independent wills in the unit moving, butting, compromising and trying to find ways to find fulfillment - both individually and as a duo. Good marriage are a harmonious blending, so I'm told.
The two are even 'opposites' in a sense, and the way the marriage develops (or falls apart) comes from internal movement - and if the movement/conflict stops, you've got only an empty shell.
But honestly, if you want to sit down and analyse your relationship in terms designed to describe the class struggle (in Marx), or the movement of atoms (Engels), or the march of science (Hegel)...then I suggest you need to put more space between your political life and your personal life.
Remember, even if dialectics works, it doesn't allow for the making of plans. It only explains things after they happen.
"Marxism has been changed; from a revolutionary theory it has become an ideology." - Karl Korsh (1950)