Game concept
Crush
The game also links it as Crushes, Crush's, Crushes'.
From the game's encyclopedia
The game's text for patch 1.20.1.2. Words in blue are entries of the encyclopedia: hover one to read it, as in the game.
Crush is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "A Crush is another Child that this Child is developing their first (rather painfully-awkward) feelings for." It is part of Special Relation. The game also links it as Crushes, Crush's and Crushes'. Patch 1.20.1.2, from game/common/game_concepts/00_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/00_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.