It isn't really though is it? It's on the cusp of being a kinetic novel in reality. People/you can either accept that...or move on as it isn't your thing.
No it isn't. Look, I'll say it straight, even if gets me a thread ban. If all the fucking alpha male (lol) whining idiots in this thread think they would react the opposite of Frank (if presented with all the same options) and fuck their girls without thought, they are either:
a) fucking deluded or
b) liars, or
c) not even old enough to vote.
Nope. As an adult with female family members (not daughters) I get the POV of Frank. It should be very disturbing to have the hots for a girl you have raised since the crib, and that you see as a daughter. I also respect that if she is curious and experiments with her step-sis, Frank accepts it and doesn´t go all drama king (even If, IRL most sane adults would have a sit down heart-to-heart with both girls at this point).
That´s why, since Frank has been somewhat "realistic" (if we lower the bar on the realistic a bit) it is irritating that he pushes his daughter, the one he has raised, into a proper incestual lesbian relationship to cope with his demons. To reiterate, in my case the relationship is not the problem. It is the pushing.
The problem is that The father of a girl, knowing that she is not sure, listening to her doubts presents a quasi-ultimatum (either break with her now or go formal now) and forces Abby on one of two paths, and at the same time he uses his position of trust (she is his loving daughter and listens to him) to present the path he likes as more favorable, in practice skipping her choice and forcing her into what he believes is better (practically coercing her) for HIS OWN DESIRES. Not to make her happy, not to clear the air between his two daughters, not because it is the right thing to do; it is because he wants abby to stay "his girl" (IE no other d**k for her).
If you tell me that THIS is sane behavior, instead of listening to her doubts, guiding her and ultimately, leaving the choice to her with no bias. Or being upfront with his bias ("In my opinion, you should...... but it is your choice") then you are the deluded liar.