I've really gotta disagree with that assertion.
If the world was crashing down, and I'm Some NPC and not a Big Dang Hero, then I'm spending it with the people I love the most - friends and family, including the person I'm in love with. If I'm fleeing danger, I'm doing it with my spouse. That's a normal human instinct, and it'd be what most NPCs in most disaster scenarios do IMCs.
Showing this in an adventure narratively reinforces what is at stake, what will be risked if the party loses - the loss, the pain, the suffering that the world crashing down will create. They're saving the world to prevent tragedies. Parents weeping over their children's short lives, or ones who want to rush into the fray because they can't stand to do nothing.
Even as a PC, personal relationships are often at the core of your motivation to do anything. You fight evil because there is something you care about protecting in this world, something you love enough to risk your life to protect it. This has often been a particular individual for my characters. Even when not fighting for that person in particular, relationships (often broken ones) might make up a significant part of the character's history. And if they don't come up in the backstory, they come up during play, when the demon king sends his succubi to distract the party or when they encounter the nymph in a secluded wood, or when they are lured by the song of the sirens or the harpies, or lured in by a hag's attractive illusion. The enemy will use your sexuality against you.
Relationships and sexuality have been part and parcel of the game since its inception, and will continue to be going forward. And they should be! It's borderline absurd to try and bar these elements from the game. They're as much a part of the fantasy world as longswords and wizards. They will appear, and when they appear, I think they should appear in diverse forms.