Nice to meet you and thanks for sharing your thoughts.
Maybe part of all this transition is thinking what I say matters. In a marriage it does, there's an obligation to hear even if you're not listening. It's so hard yet so crucial to learn how to step out of the box of 'us', step out of the container of the 'hurting me' and look dispassionately at the situation.
Priorities changed for one or both.
Dis-ease ensues with priorities the focus usually shifting more from the relationship to the family, the job, nurturer, provider.. to what's familiar, what you're good at.
Distress increases as the gap widens as their functions become separate but still in the umbrella of family.
Disgust bubbles as dis-ease and distress roil. You're held together by the beliefs that bind you, not by the foundation that built you.
Distraction seeps in.. at first innoncuous then sweeping. The glue of the relationship on one or both sides starts to weaken.
Entitlement enters. No more feeling of two being one, just one alone with the adversity of their marriage. The foundation's eroded, added by escape; the family unit burnt by the new searing need inside.