My ex keeps coming back even though hes' been in a relationship with someone else months and says he loves her but when they fall out always comes back to me and knows how much I still really love him

Because you let him, you are a safety net when things are having trouble, then he goes back.
If you shut the door, don't talk to him and don't let him, you will get over him and move on.

Your other answer about a "safety net" is really great, and true. He comes back to you because he knows you are there. It's like a cheating husband having an affair, and always comes home to his wife, who keeps telling herself that everything will be OK.
Well, it's time to move on, wake up to the fact that if he really loves you, he would respect you, be honest with you, and want to be with you all the time. He doesn't feel any of that. Please meet some new people, and start living life with fun. Good luck.

He keeps coming back because he knows you will take him in. I would stop this, and find myself some new friends, and a new boyfriend. You can do it. I was divorced after 7 yrs of marriage. Life is not always good, but we make the best of it. You can do it, too. Move on and find a happier life with someone else. Best of luck to you.

He keeps coming back because you keep taking him back.

they fall out always comes back to me and knows how much I still really love him

He knows you love him more than you love yourself, and that makes you an easy target for his BS, while he looks for his next adventure!

He comes back because you let him. It's really that simple. As long as you keep your revolving door unlocked he will continue to use it. If he really cared about you, he would stay with you.
Ask yourself why you keep doing this to yourself. You are the one in control.

Listen I totally know your pain This is my life as I type. Me and my X have been going through this for over a year. I'm finally able to understand and slowly move on but I had to realize that was his pattern not to mention I discovered he has some childhood mommy issues. There are many possibilities. Some of which include certain behavior disorders, for instance Borderline Personality Disorder or bipolar disorder, comes to mind.

It could be just for sex.
It could be that he does not like to be alone and when he finds himself feeling alone (even when hooked up with someone) he believes he can solve that alone feeling by going back to you.

As much as you love this man, you are better off realizing that he is very unpredictable and unstable and that you will be heartbroken over and over again if you keep seeing him.

You will be better off to never date him again even if you never stop loving him. I worry some that you have your own set of issues(not saying this to be mean, I've go a lot of my own after my sudden and devastating break I discovered I had post trumantic stress disorder) because you love someone that behaves this way, rather than being angry and giving him the cold shoulder and after the first hurt and pain of a breakup wears off you continue to love this man and hope that it will maybe some day work out for the two of you

You are going to hurt for a while. But, it will get better. And sometimes it is good to not follow our heart but to use logic and know that this man is going to hurt you over and over and to stop dreaming about him and know (even if it feels differently) that the man is either a huge jerk for yo-yo ing you around as he does, or has a serious psychological problem, or problems, which, in both cases you are better off single than with him.

I am sorry for whatever you've been through in your past and sorry that you still have feelings for this man. I wish you the strength, the courage,and the knowledge to move on and towards better things (and better men).

The no contact rule is great for situations like these. It's the only way you'll ever successfully get over this guy. It'll be really hard to do at first but it'll be worth it as you'll get yourself respect back and be open to seeing how many other great guys there are out there