Yeah thats what it is called! I broke up couple of relationships because of this. Then I realized there is some problem with my thoughts and how i was working with them…

I understood that by being jealous and thinking about the past of someone, I was controlling them. I was behaving like an egoist, jealous, judgemental and insecure person.

One realization was there is nothing wrong and right in this world. We humans have made some moral rules and based on that we judge people for their behavior while at the same time thinking we are better than them. From the childhood only we are made to believe lot of morality about sex. We wouldn’t be having any problems with our partners having sex in the past had our society portrayed it in a different way. Having sex before marriage, with someone old, without loving someone etc is our mind’s judging the person. Knowingly or unknowingly we think in our mind that I would had never done that so how can she do that? Then we start judging that person as someone bad, someone without morals etc. But if we see deep inside us, we will find that we are neither good in lot of matters. We also have taken decisions in past which we are not proud of.

I have OCD and I too obsess a lot about my partners past. Another realization was that if you break up the current relationship due to jealously, your mind will start believing that their is nothing wrong is judging person who has some kind of past. Next time you try to date someone new, your mind again gonna bring this topic and you will be in much bigger trap of mind…

What worked for me?
1) Whenever those thoughts come up in my mind. I mindfully think and sometimes say to myself that this is my insecurity and ego coming up again to prove me that I am a better person than her and she is wrong. Sometimes I extend it saying that I am noone to judge her. If she was happy that time, that’s her life. She didn’t bother anyone, neither she hurt anyone by her steps. Being in love is all about being happy for other person’s happiness and I dont want to be a selfish person.
2) Then I start diverting my mind to some other activity like my work, cleaning stuffs etc. Sometimes when I don’t have anything to do I start doing mindfulness meditation by concentration on my breath etc.

What this does is that with time your subconscious mind starts accepting that maybe this thought is not so important for you. Once you start diverting your attention to other stuffs, your mind will slowly start accepting and then the jealously will go down. Because more attention we give to this emotion of jealousy and keep on ruminating about it, our brain accepts that this topic is really so important for me and I need to be keep thinking about it.

Its not easy and it takes lot of time.. Maybe a month before you start seeing changes in your thinking process. But its worth doing.
Mindfulness practice along with above steps has really helped me in moving forward. These emotions are still there and sometimes they do bother me but its very easy now to get over them.
By moving forward and slowly learning, you will also find that you have started judging people less as you used to do before. Belive me it brings lot of peace and happiness in life…

Hope it helps you…
Abhishek