Trust is the keyword here, but sometimes you do have to keep a
hand in it.
I knew how you feel right now, cos I fully trust my gf, and to the
extend that I allow her to go out 1 - 1 with other guy, cos its her
gan didi, so i thought nothing will happen. I was wrong big time.
In the end, she and he really did something wrong (nono, not sex)
to me. 
Although she said
she still love me and do not have any feelings to her gan didi, but
she called for a time out as she said she want to find out if she
had any feelings for me anymore. I still love her, thats why
although I was hurt badly, I still am waiting for her ans on this
friday. And I hope the ans will be the one I really wish to heard
de, and that is she still have feeling for me. 
So my advise to you is, trust her enough that you will know she
will not betray you, but at the same time, do remember to keep a
hand on her. Remind her that she is attached and the up most impt
thing to her is you. Good luck to you, do not fall into my foot
steps 
