Is there any flaws in me that ruined this relationship?

Everybody has flaws. It's just human. I'm sure you have notice that your partner too has flaws. Be someone who loves everything about you. Even your flaws. Relationships take a lot of hard work & compromise. Explain to your partner how you are feeling.

There could just be a problem with the other person in a relationship and they need to work on themselves

Your flaw is your belief system. People who become easily jealous are those who are insecure about themselves. For several reasons, they follow a belief system that claims that they are not worthy to be with their ideal partner. They fear that when they enter a good relationship, they will eventually lose that partner. What we fear causes us to attract the very things that we are trying to avoid. If you believe that you are unworthy, then that is how you will project your behavior. Jealously is strengthen by the fear of losing someone. Jealousy can cause people to behave overly controlling towards their partner. They may set limits on who the partner can and cannot interact with. In many cases, eventually the partner will grow tired of the controlling nature of the jealous person. The partner will then breakup the relationship and move on. In this case, the very result that the jealous person had tried to prevent had indeed occurred. You need to be honest with yourself, and recognize your own self limiting belief system. Take your failures from the past and learn from them. Use those lessons to strengthen yourself. Life involves a series of failures. Those who succeed the most take past failures and use them to reshape themselves into a stronger version of themselves.

There's flaws on everyone. No one is flawless, you just have to find that someone who doesn't care about those flaws and love you for you.

In a relationship it takes two hands to clap. Both parties are involved in it and both parties has to want to make it work. There is no one person to be blame if the relationship does not work out.

A relationship is a two way process. There can never be flaw at one side but both sides would have flaws that may have put an end to the relationship. It happens for the better because at every breakup you get close to finding the one you really love.

In my thoughts, NO. I tried to have an ex back one time after he left me. He discovered the grass is not always greener on the other side ( that's his problem ) and I discovered myself after a while and was doing just fine without him.