Kev is still smarting for the 99 problems of Ethel that night, and can't even get it up for their eighteenth bout of sex today. "V, that girl needs us. I mean, you heard that messed-up story of hers. Not to mention she thought I wanted to have sex with her today." That one gives Veronica pause, but she's steadfast that the "freak" is not going to live with them forever, or even next week. Things do not end well, but you can see that Kev isn't giving this up without a fight. He grew up in foster care and it's clearly scarred him, but it seems like more of the fact that his Debbie part is coming out and he honestly can't handle the idea of losing this weird little girl to the storm.
Karen climbs into bed with Sheila, who is weeping, and they discuss whether or not Frank has abandoned them. Karen assures her that this little sojourn at the Gallagher home is only temporary, and things get way fucking dark: "Lip says he'll be back to normal as soon as he starts drinking again," she comforts her mother, and just like that the whole cast basically climbs aboard the fact that no matter how transient this Perfect Frank thing is, it needs to end immediately so they can all go back to their normal lives.
I mean, no chance was Frank going to turn things around, but it's still a fairly awful concept to consider that both of these households are now set up in such a way that they will fall apart without Frank being a mess. And not just in a clever-writing or clever-concept way, but in a way that strikes to the heart of the matter, which is: Entire families are built around the addict, you make these compromises over decades in order to keep everybody alive and protected, you make them and their disease your fucking keystone, and that's sad and gross and everybody -- Lip, Fiona -- are constantly being tempted with a way out.
But as essential as each member of these families is, to the working of the overall mechanism, the fact is that if you pull Frank out of that Jenga party the whole thing will fall apart, because they have been covering for him for so long, taking care of him and each other, that they're bent into unimaginable arthritic shapes around him. Because Frank's drinking is the center of their lives, their lives collapse without it, which is the "dependence" in codependence. Which, it's fun to blame the victim and all, but if you look at it that way it's both strength and weakness at once. The inability to remember that life could be better, the inability to remember that surviving is not the same as living.