Unfortunately, almost all guys have that insecurity and possessive instinct within them. Most manage to keep a lid on it most of the time, only showing it when they truly think something might be up. But for some guys, that lid is off all the time and whenever they get with a girl they are forever worrying about what she is up to and what she might be doing. Even if she is having tea with an aunt, then can only ever envisage her in the middle of an orgy. Those type of guys will go throughout their entire lives fretting and sad about whichever women they are in a relationship with at the time. For the women involved, the time with them can be harrowing. They may truly love the guy, but his possessiveness and domination can easily push them away. For women, there are three distinct stages to dealing with a possessive guy.
The first thing they will try to do is understand. They may ask about previous relationships and things that might have gone wrong. Worryingly, they will often start to blame themselves and look at their own behavior, even if they are in the right. Understanding though is a good idea, as they only way the guy will realize his problems is through talking and sharing. Ideally the women will push him to seek counselling before it becomes too much of an issue.
The next stage is some action, either relating to his behavior, or to hers. Ideally, she will stage some kind of intervention and tell him at what point he is becoming too overbearing and causing problems for her and the relationship. He may listen, he may not, depending on whether he wants to face up to his issues or not. Either way, it is good for the woman to present eh boundaries to the guy so that he knows where they are and what happens when he oversteps them. Hopefully, the woman will not start to adjust her own behavior to fit in with the dominance. This may take the form of not going out, avoiding male company, or avoiding friends altogether. If she does this, then the man has won and he will never change his behavior.
This is the nuclear option, but he one that a woman should always make sure she has at her disposal, and uses if things get too bad. Ideally, she will have set boundaries before and warned the guy what will happen if he continues to be too possessive. If he has been warned then he can have no objection when she leaves. Of course, he will blame it on something else, probably another man, but no woman should have to put up with being treated like a possession, so should leave whenever she feels the love being sapped out of the relationship.