Actually, I missed (i.e. not yet played) those scenes, but I can assure you that I have met and seen people even older than her, and not only women, who would come out with that kind of ideas.
In the case of Emma would be probably imputable to her first big love and first delusion. In the case of older ones, can be fear of being hurt, arrogance, and dumb ideas like "I had already sex, therefore I cannot be naive" which makes it impossible in their head to realise they trying to hang of a fantasy while being fooled and fooling themselves (in case you wonder, no, it is not theory, details were different between different situations, but more than one, some arriving really to that level of denial, and we are talking about 25yo or even more).
A difference between sexes can be that often that kind of behaviour in men is expected to go on the creepy side towards stalker, but it is not a rule, and on the other hand, there are also women who are creepy stalkers.
