It was brought to my attention that some people struggled with getting all the endings, so here's a quick, spoiler-free walkthrough on how to get all the different endings!

Ending 1
Ask about the portraits
Panic

Ending 2
Keep quiet
Confess your love

Ending 3
Ask about the portraits
Play along
Confess your love

Ending 4
Ask about the portraits
Play along
OR
Keep quiet
Ask about him instead
Refuse

Ending 5
Same as ending 4 but ask him questions instead of refusing at the last 2 menus

Restart the game after getting all the endings for the final end!