Sometime, guys lack of trust and have fear of losing her in the relationship bah. They set stupid rules to limit the gf and unwittingly wanting to destroy the relationship..
And some guys are just genuinely concern about the girlfriend's safety.
I think ultimately boil down to what is really your intention?
If it is the former, then the consequence would be much harder to handle and if it is out of genuine concern, i think in the end, the girlfriend will understand bah.
Just have to check your intention.
Relationship is not about owning someone