This is my Rom-com idea
Kirk and Marcus are Friends With Benefits. She gets pregnant but she really likes McCoy who won't make the moves on her because he's still too traumatised over his divorce. Meanwhile Spock and Uhura are sad because they are trying for a baby and can't have one.
It all ends up that Kirk goes on a one-way mission and McCoy promises to raise the baby as his own with Marcus.
Or we can go the way of my preferred option that Marcus isn't foolish enough in this timeline to get involved with one James T Kirk.