Love vs. Oneitis
Oneitis is the total obsession with one girl before you have had sex with her. Oneitis is a beta male belief/behavior.
Love is the romantic feelings for a girl that you have slept with. That you want only her as she fulfills your needs. Your love is contingent upon her good behavior and something that she has earned.
The distinction between oneitis and love is whether or not you have had sex with the girl yet. if you have had sex, then it is love. if you have not had sex yet, it is oneitis.