what are sad letters and where can i see marriage partner illustrations again?

[tsbasilisk]

can't find them in gallery
instead i found sad letters what r they

[58]

sad letters are a somewhat new addition to the game which seems to be sent when you have a high relationship with a character other than the one you married. a sad letter is sent by the person with the second highest relationship (after the married one) after you see the marriage cutscene.

sad letters and marriage partner illustrations can be found in the bedroom rather than the gallery. each character you've married will have an album with all of their illustrations as well as event cutscenes