I think the issue here is trust, how to verify who the gf is really going out with?unless they took a groupfie and post on FaceB and tagged the location of the outing or TS offer to pick her up after the outing...
If the trust is built up in the r/s, shouldn’t mattered who she hang out with, the only person that no one should trust is the ex! Haha.. very likely will trigger something if meeting up with the ex.
Just my point of view
