And the answer is of course, "Yes", it does happens that a female (or a male) will decide that they do not want to accept the other. If she (or he) isn't interested in breeding, the mate is usually unsuitable, or unable to mate, or resources are scarce. If a keeper is lucky (and this is rare to happen), the two will live happily as platonic friends. What usually happens, you guessed it, territorialism, fighting, aggression, etc. Which, back to my answer, is why we watch closely for signs of aggression as Phelsuma can easily go the less favorable direction.
I was on the ball and in the court. I just focused more on comments #3, #4 and #5.