A simplistic view:
A woman will forgive a man who cheats if she is convinced he shagged other woman yes, but he does not really luv her (the other woman) and appears remorseful. To them love is paramount.
But if the man says he loves her (the other woman) then for the woman in the r'ship, its game over. Coz women are more emotional.
Men are physical, think about sex quite a lot and the actual sex act means everything to a man - so if your significant other is dishing it out, to men it means she is giving out her all. Nothing left for him. Even if she says she loves him, he will say,'...na mbona ulimtolea suruali...'
Coz to men sex is more impt.
So for men that marks game over...