turns to very mean to me

[Ju]

How do we describe one treats me very nice when he needs my help and support. After his problem has been settled and he doesn't need me any more, he turns to very mean to me?

Thank you.

[BobK]

He is showing 'cupboard love'. But this idiom isn't exactly the same, as a person who shows cupboard love doesn't have to be - and return to being - hostile.

b

[Ju]

He is showing 'cupboard love'. But this idiom isn't exactly the same, as a person who shows cupboard love doesn't have to be - and return to being - hostile.

b

Since 'cupboard love' isn't exactly the same returning to being - hostile, what is the one exactly what I am asking?

Thank you.

[allenman]

How do we describe one treats me very nice when he needs my help and support. After his problem has been settled and he doesn't need me any more, he turns to very mean to me?

Thank you.

We would probably say idiomatically "he's a user" (in other words, he uses you to get what he needs)

One slight correction in what you asked... you should say "he turns very mean to me" instead of "he turns to very mean to me"

Not a teacher

[wq.denis]

How about "having 2 faces"?

a newbie

[Raymott]

How do we describe one treats me very nice when he needs my help and support. After his problem has been settled and he doesn't need me any more, he turns to very mean to me?

Thank you.

This is not exactly what you want, but I'll add it anyway.
A "fair weather friend" is someone who is your friend when everything is going well, but who drops you whenever they're called upon to do something, or at the first sign of trouble.