Egalitarianism (with regard to marriage) is the view that in a marriage husband and wife should agree before any decisions are made or actions taken that affect the family (whether that be just them as a couple or includes children). Whether one or the other is called “the leader” of the family is irrelevant (although, of course, most contemporary egalitarians do not like that designation especially for the husband!). I judge that a couple has an egalitarian marriage insofar as neither one makes any decision or takes any action that affects both without advice and consent of the other.
If a person does NOT agree with that, then I worry that he or she is in a hierarchical, dysfunctional relationship that both subjects truth to power and will lead to abuse (not necessarily physical, but not all abuse is physical). I suspect that MOST conservative evangelicals who think they are complementarians, when push comes to shove, will agree with my stated thesis above and then, at least in that moment, be really more egalitarian than complementarian (if complementarian means anything different from egalitarian).