Your gf really need to get herself occupy with somethings else before their relationship sour again of all these 'TRUST'.
You need to trust someone to be with him/her everyday. Otherwise it will be very difficult for both parties. Consultation from the professional might really help.
Recall what you used to enjoy doing during courtship, (e.g short trip to malaysia, trekking,etc). Continue to do it even though you are married for million year. It really help to recap all those lovely memory.