This might be a petty question compared to most people here who have real problems but anyway here goes...

Theres a friend of mine if i can call him that, well we have known each other for almost 10yrs now , we get along very well , spend time with each other, enjoy each others company . But ... only when its convenient for him to do so .
Which means when he has problems in his life and needs to escape ... when he needs somebody to confide in and when he needs advice.

When things are ok in his life and everything is going well , i wont hear from him, he wont answer my calls , wont reply to my msgs.... then suddenly one day he will call and say life is so messed up and i need to see you. I get so involved in his problems that i just forget how he treated me, i feel sorry and agree to see him and the cycle goes on and on.

Am i just a sucker for punishment?
Does this friend even deserve to be called a friend ?
Should i just treat him the same way he treats me?
Useless telling him how i feel bcoz he apologizes and does the same thing again!!!