Your friends DC may visit there parents more often if they live quite near but there is the possibility your DS's GF may not be the one stopping him visiting on his own.
I do remember once DH and I were married, I was the one suggesting we visit his DM, so she actually saw more of her DS because of me.
Nothing I did ever pleased this woman, the reason, I had stolen her boy. DH picked up on this and sadly, in time, she saw less of him.
Problems in Harry and Meghan Marriage
So it begins….. Streeting resigns
Times article claim that Waspi women are tone deaf and should read the room



]. Even the slightest hint that you'd rather see him alone could be misconstrued by his gf so I'd tread very very carefully. My son did have a gf who didn't talk [they lived here at weekends for quite a while] and that was really difficult; I used to hide away in my computer room or bedroom when she was here without him 