Mantus, I think what you are describing is the slow process of taking someone (or the relationship) for granted... to assume that just because the relationship is "comfortable," then it must be working okay. It may be ignorance, but in a relationship, being ignorant is essentially apathy/laziness, not wanting to constantly discover more about the other person... and I think this attitude still boils down to selfishness.
By taking someone's presence for granted, you are denying them the daily recognition and attention that SHOULD happen when both people are working hard to communicate and connect on a soul-level. And yep, it's work. Hell, it's even more work when there are kids involved, and you have responsibility to connect on that same level with your children each day, in addition to your partner. By no means is ANY relationship something that comes naturally, easy, etc.. it is always work, especially communication (as Sage said)... but it's damn good work, with LOTS of benefits.
