Most of the other members are okay with letting Han & LK work this out on their own.
But Seungmin struggles with it, a bit. He has so much love for all the members, & wants them all to be happy & loved-up to their hearts' content.
He can't help but feel frustrated that there's no solution where everyone gets that.
Han is an easy target for that frustration. If Han would stop being jealous, then LK would be happier.
But also SM knows that this is unfair to Han.