Can rivals ever be best of friends?

Can two people who have been in contention for same thing or better still, can two women who at a time in their life shared same man and even had children for the same man...ever get together to be best of friends?
Well that seemed to be the case between Annie Idibia (2face's legal wife) and Sumbo Ajaba, who has two kids for 2face.they being friends to the extent of remembering each other's special days such as birthdays this behaviour should really be encouraged