Five Children (54eps) - family drama with multiple couples, one of the best. Primary couple is a widower with two young children and a divorcee with three young ones.
My Golden Life (52eps) - 25 years earlier, a very rich family had their small daughter taken but no ransom was ever demanded. At the same time, an ordinary family had just buried one of their twin daughters. They found what seemed to be an abandoned child in a deserted countryside area and raised her under the dead child's identity. The father went bankrupt some years later, and they have been living poorly when their daughter's true identity is discovered. Focus is on the two very different girls and the two very different families. One male lead is from the rich family (and more than a little stalker-ish). Not as good as Five Children or Father Is Strange, but held my attention.
Never Twice (36eps) - about the long-term guests at a six-room inn in Seoul, many of whom work at a large hotel nearby or are connected with it. Multiple couples.