i can't imagine would've could've should'veing them (couldn't write them in a relationship with such power imbalance) or london boying them (i could never make them british). i also couldn't superman them cause i don't like the frail damsel waiting for their man to come back to them trope.
otherwise in terms of dynamics i cannot think of any other song that couldn't be markhyuckfiable, besides the obvious ones which simply wouldn't work cause they are not relationship focused (like marjorie or me!)