Mary and Sharon Bishop-Baldwin were jubilant after winning a decadelong fight for the right to wed in Oklahoma.

But eight years after tying the knot — on the day they won their lawsuit challenging a state ban on gay marriage — and seven years after the U.S. Supreme Court affirmed same-sex couples' constitutional right to marry, they no longer take their union for granted.

While they're happy that Congress is moving swiftly to ensure nationwide recognition of same-sex and interracial marriages, they — like many in LGBTQ communities — are frustrated it's even necessary after so many years and ar...