It's easy to see how B'Elanna drew inspiration from her own childhood when re-writing the Doctor's holo-family. The son's annoying obsession with all things Klingon is clearly inspired by her Klingon mother. The Doc's holo-wife is also inspired by B'Elanna's mom, who had an obsession that harmed the family; instead of an obsession with Klingon culture though, B'Elanna just changed it to the mom being a workaholic. The reckless, athletic Belle is possibly inspired by B'Elanna herself as a child.
The previous episode, "Before and After," ended with everyone discussing the possible future Kes saw. Kes didn't give everything away, but there are hints that she let slip at least some hints to some of her friends between these episodes.
The Doctor is inspired to create his own holo-family now, in the episode immediately following one where his current closest friend saw her alternate-future family. The Doctor even states that hearing his shipmates talk about their families inspired him to create the program, though he doesn't single Kes out specifically.
Tom and B'Elanna begin openly flirting in this episode (when Tom catches her reading a Klingon romance novel).
Well, Fridge Awkward more like but: this episode is directly after "Before and After". Kes has dinner with the Doctor's holographic wife and children, while sitting next to B'Elanna. That must have brought up a hurricane of uncomfortable memories (from the now undone future) that Kes was probably trying really hard to forget.
To recap: in the previous episode, Kes essentially allowed her own daughter and grandson be erased from history, to save the life of B'Elanna, and her future relationship with Tom. Kes has dinner with a "family," whilst sitting right next to the woman who inadvertently is the reason she no longer has hers. And she can't tell anyone.
