name animé characters who are in l’amour with someone older than thel,like a teacher ou a big brother of someone ...

The 15-year old Stella towards the 16-Year old Ikki.

Kokonoe Rin

I couldn't really think of anything and I don't know if this would count because one despises the other, but...
Soul and Blair? :P

maybe Tatsumi X Esdeath from akame ga kill

Kriem and Jake from Tiger and Bunny. We don't have official ages, but she was probably around 16 when she met/fell for Jake, who must have been in his twenties.

Anzu has a crush on her teacher Naozumi Tsuchida. Both from Hanamaru Kindergarten.

Yuki X Kaname From Vampire Knight. They are siblings and fiancée too!!