The focus on So-hye's weirdly melodramatic disease symptoms is removed here for the sake of instead focusing on Joon-gi's more traditionally tragic melodramatic disease symptoms. The results are about what might be expected. The acting is unavoidably corny as the emphasis is instead placed on the inherent empathy of the situation. Friends don't like it when other friends are in for a bad time. Even if Hae-seong hates letting go of So-hye for even a moment, well, Joon-gi is a bro. And that's what bros are good for.
Elsewhere the plot is rather listless. It's hard to imagine that there are going to be three episodes left when pretty much all of the significant conflicts have been solved. Jin-tae's generally pathetic attempts to deal with Seol are fairly half-baked given that he can't really explain why she fled the house and got completely plastered in the first place without outing himself as a domestic abuser. Jin-sook's plan also fails for the similar reason of her just not having any useful leverage.
Partially this all works to the drama's greater point- real friends aren't going to ditch you over a one-dimensional blackmail scheme. If someone is being abusive, the best possible option is simply to sever. Life is short, so any excuse for a party is a good one. The trouble with all these transparently simple goals is that they're so easy to accomplish that leaves fairly little in the way of plausible conflict for the remainder of the cast to deal with.
On general principle I get annoyed when dramas are reptitive, but in the case of "Fantastic" the life lessons are so simple and generally well-natured it's hard to get that mad at the drama. It helps that by and large the characters are generally fairly likable, and even their flaws tend to be well-integrated as positive personality traits on the flip side. So-hye, Seol, and Mi-seon all have fairly aggressive personalities, and this is fine, so long as they're being aimed properly.
All the same it leaves me with fairly little to discuss that I have not repeated several times already in previous reviews. "Fantastic" consistently accomplishes what it sets out to do fairly well- the drana just doesn't really go very far beyond that. I just hope that the production team accomplished its fill of melodrama with the last few sad, happy scenes this episode and that we're just moving to a boilerplate happy ending from here.