No,never! "Once a lier, always a lier" It's a human trait when we go through a bad thing.We forget all the good things. Same as, when someone cheated us. It always remain in our hearts. Even the person change, even we spend more beautiful relationship than ever even we pretend that we forget and nothing happened in the past. But once the other person do something wrong again, even a little thing. It reminds us all the bad things, he/she had done in the past. Noted : If someone cheated you so never believe on her again. Because she is not meant to be with you.
You can never be there for them you just have to let it go sometimes, may be this is what is good for them and if you cherish their happiness then let them be, it will certainly give you peace. 🌸