Should I address the elephant in the room?

[TheNovelist2000]

Before the answer, a question.

Do you want to?

Its possible to write the story as you describe and just never get into where the father is. Immerse the reader in the story and let them enjoy it. Many will without thinking but where's dad? Once they're done they might wonder, and it won't be all of them, and at that point they can make up the answer they want. Divorced and gone. Out of town and unaware of this taboo affair, passed away?

It works as long as the story and scene between mom and son is well delivered.

If you want to bring dad you can, but be careful how and when you explain it. You don't want an exposition dump to ruin any momentum in the scene so it has to be established early on, and, again your choice, it can be done in a few lines. If he's not in the story why waster too much time on him?

If this were me, I'd do this without bringing him up.

Ok. I've established in the beginning of the story that the dad is only going away for two weeks. I've read some of the tropes you've proposed in another thread: an asshole dad, an inattentive dad, ect. Well, somehow I've sort of written a dad that doesn't fall into any of those tropes, as far as I know. The story begins with a passionate all-night long sex between Melissa and her husband Josh Senior. Josh Senior is written to be a pervert, making her sit on his face, ect. They were already getting at it even when they were just teenagers, with him taking Melissa's anal virginity at only 18.

The story is about how loyalties can shift easily when the dad's away, when Melissa comes across a better, younger version of Josh Senior---Josh Senior 2.0 (a.k.a Josh Junior).

She will have to eventually reconcile with that fact when he inevitably returns after two weeks. By then, he will be coming home to a place ruled by the son. So, if we bring him into the picture now, that drastic transformation will never happen because Melissa definitely will have to deal with guilt and her passion for her husband might be reinvigorated. If she talks to him now on scene, I can see him sexting or playing with her over the phone, which might take away her passion for Junior.

My plan is to summarise how she kept their phone calls short and avoided Josh Senior as much as she could during the two weeks before writing about how Josh Senior finds his new, changed home.