Is it ok to love someone that cheated on me but I still want to be with them even they cheated on me three times?
Only you can truly answer this question. But from me as a person who was with someone who cheated on me multiple times, it will get old. You will get old in the process. Being cheated on is a form of abuse. It will break you down. Your self esteem, ego, pride, confidence and security will suffer immensely and then your own mind will turn on you. It's a harsh situation. It takes a long time to recover and it's hell in the process of recovery.
Love has to be from sides or it's not real. To say the difference of being with a cheater compared to being in a happy, healthy relationship is like night and day is an understatement. Nowhere in any definition of love is cheating. It's not love. In fact, it's the total opposite. It's mental abuse and anguish. You can't love her enough for the both of you. You can't fix her. She will never treat you as a person because you have allowed her to do this to you. 3 times is probably more than triple that.
It's understandable that you are in love with her to an extent. Do yourself a favor and ask yourself what love is to you. I will bet that her sleeping with other men isn't part of that definition. Or being lied to or being deceived and betrayed.
As one other answer said, learn to love yourself. As long as you are with someone who doesn't give a rat's ass about you or your feelings you will never understand what real love is. It needs to start with loving yourself enough to know you are worthy of more. Being brave enough to say you won't tolerate it and being strong enough to move forward and find someone who values you and your heart. It's not always easy to do but it's important for your state of mind. Letting her do this to you will take your heart into dark places and like I said, it can be a long recovery.
It took me many many years to learn to trust. It took me many years to convince myself that I was worthy and I am proud to say the journey was worth it because I am now happily married to a wonderful man. But I went through hell and it was mostly due to staying with a cheater way too long fantasizing that he would one day love me….I ended up hating myself because of it. If I could go back in time I would've left the first time. But I waited and I'm sure it was a dozen times….
I wish you the best and hope you move forward and find someone that will appreciate and return your love.