This page contains information on the many Supports and Support Levels that can be obtained between Characters in Fire Emblem: Three Houses.
Support Bonds Chart and S-Rank Guide (Romance) - Fire Emblem Engage Guide - IGN
FE3H All Female Confessions & S Supports - Fire Emblem Three Houses
Fire Emblem Three Houses: 5 Character Romances That Make Sense (& 5 That Never Will)
FE3H Marriage / Romance Ignatz (C - S Support Conversations) - Fire Emblem Three Houses
Top Tips For Fire Emblem: Three Houses
Fire Emblem Three Houses: A Guide To Every Possible Romance
IGN has the support information up. : r/fireemblem
Which of the early Fire Emblem games is the most well thought-out? - Quora
Fire Emblem: Three Houses – Cindered Shadows (Nintendo Switch)