when called up by a girlfriend

When called up by girlfriend because she has relationship problems, the wise thing to do is to is always listen and repeat what she talks and then occasionally throw in something like “I can’t believe he did that!”; “I am so sorry to hear that!”; “he will finally grow up one day” “really, oh my god!”…

That was exactly what I did, when this girlfriend told me about her boyfriend cheating on her and thinking about breaking up. This was a typical perfect couple, the girl is Chinese, guy French, used to live together in Paris. Six months ago, they decided to move to China for a new adventure and get married over there. They both found jobs, but one ended up in Beijing and the other in Shanghai, the two places don’t seem to be so far away seeing from here, it is after all 1h 30 flight a part. Numerous fights during the 6 months and she caught him cheating couple of times, now seems everything is too late. I ended the conversation with her not giving much real advice other than some politically correct BS. A couple of hours later, it bothered me so much, I called her back:

Ana: I thought about it more, I think if you still love him, you should forgive him
GF: how? Even if I forgive him, how can I trust him?
Ana: Then try trusting him
…

Maybe it is only easily said, would I be able to forgive just like that? What if she never found out that he cheated on her, wouldn’t it have been easier? Am I just lucky to have dated honest guys in the past? Or were they just better liars? Or because I never tried to find out the truth? So is my girlfriend just suffering because she made too much effort to find out about the truth?

I suppose I only want someone who is sincere about his feelings, but I don’t need all the truth, I am not interested in knowing all of it if it is going to upset me.