Should I write:
'I'm your teacher, who does not love lazy students'
'I'm your teacher, who do not love love lazy students'?
I cannot decide whether this "do not" belongs to "I" or "your teacher" in the sentences.
What do you think?
"does" agrees in number with "who". "who" refers back to "your teacher", third person singular. Try looking at it this way,
Plural: They are the ones who do not. . . .
Singular: S/he is the one who does not. . . .
I am the one who does not. . . .
I am your teacher. The one who does not. . . .