Romance is a decaying orbit in these stories, and marriage a landing — although whether on land or sea is up to the characters as much as the author. There’s that air of glorious inevitability about it, extra-human forces dragging and pulling and a glorious jewel crouched there at the bottom, the toad in gravity’s well.
Such an accepted law that it’s not even necessary to show the actual landing anymore. Or even the reentry. The god of love neither speaks nor remains silent. A look in the eye, an untimely (and unrelated!) blush, a comment by a third character (usually a child), and, well, the happy ending is implied. A history of unhappy relationships, parallel tracks, the lack of other single characters (a big clue!), so on, so forth.
So our cosmonaut, let’s say Lourdes Markfeet, spiralling down towards the big fat globe of Bruce Skin. They’ve earned this pyrokinetic equalization of velocity and vector — between the two of them they’ve solved seven murders, prevented two international incidents, and fought off fourteen (fourteen!) alien invasions. They work well as a team, and there are worse things to build a marriage upon, though studies have shown that relationships formed under stressful circumstances, like wars or college or being framed for murder, seldom hold up when the stressor is removed. But you never know, right?
Through the viewscreen, the planet looms. Markfeet braces herself for contact.