As a serial writer, I have come to the conclusion that "happily ever after" exists only if that's where you end the story. But stories don't end there, they keep going on, and sometimes something changes. (See Sondheim's Into the Woods!)
I have a "happily ever after" family -- ups and downs and in-betweens; they meet, fall in love, have trouble, marry, have a family, live long lives in a big cluttered house, see their kids grow up and marry and have THEIR problems; one dies first and the other follows years later. Probably that.