I disagree
I don't think loving more than one person is selfish and I think as long as everyone in the relationship is happy there's nothing wrong with being in a relationship with more than one person or marrying more than one person. My girlfriend and i have been in an open relationship for quite a while and we've both been very happy with it.
I think Scandal choosing to marry both women whom she loves is very unselfish. It woukd be selfish if she forced Liana or Knockout into this marriage when they werent happy to share her love. But as all three women are happy to be married together I don't think there's anything selfish about it at all. I think its heartwarming and lovely
There's nothing wrong with an open relationship if both partners in a relationship agree to it, but Knockout and Liana don't even know each other. She didn't even talk to them about marrying them both. So instead of making a decision like regular people would, she chose the more selfish route of having them both.
But all three of them being happy and and Liana's friends being happy is what makes the scene so brilliant. In real life, that would never happen. In real life, almost all of Liana's friends would object to such a thing. And we probably wouldn't be seeing Liana being so readily open to the idea. But that's what makes it so great, a situation in which almost everyone would be utterly opposed to, especially in the United States, they're all just like "It's cool." It comes off as brilliantly bizarre, which is what Secret Six is supposed to be.
I would also disagree that the Six are horrible people. They're anti heroes and most of them are deeply damaged screwed up and possibly even insane. But I don't consider any of the Six horrible people except for Cheshire
Cheshire is just the worst of the bunch. Nuking Qurac made her an irredeemable person. Even Deathstroke felt horrible for the role he played for nuking Qurac, Cheshire on the other hand, not so much. The mere fact that the Secret Six tolerated working with Cheshire kinda goes against the idea that they're not horrible people.
The missions that the Secret Six take involves them lying, cheating, killing, maiming, and stealing. Again, kinda goes against the idea that they're not horrible people. The only time they come up as somewhat heroic is that their opponent is even more horrible and villainous. Their only interests is in themselves.
The only members of the Secret Six who weren't flat out horrible people were Black Alice, who is a teenaged girl and still maintains some innocence within her, and Bane, who ended up going full on villain in the final issues.
I didn't find it messed up at all. I thought it was touching and beautiful. One of my favourite scenes in the series and it made me

to see my favourite member of the Secret Six find some happiness
I thought it was one of the best scenes in the book for different reasons.