Just replying here since it's first search result thus will hopefully help people.
'YOU and ME and HER' aka 'Kimi to Kanojo to Kanojo no Koi'; one of the best know examples and was the inspiration for below.
'Doki Doki Literature Club'; very close to the original game though lacks any erotic scenes
'Sensei Overnight' & 'Lessons in Love'; two similar games which are very meta. They don't exactly break the forth wall for the player, it's more like the protagonist is experiencing the breaks.
EDIT:
'Dissonance' & ' Lost in You' are two more games like SO & LiL