“Yes, RY and Rabbeim will not let bochurim go to places that have tennage girls”
Interesting….I was an invited guest at the home of my RY and many Rabbeim, all who had teenaged daughters present at the table.
As for young couples inviting each other…my Rabbeim stressed the importance of the different families in the kollel to be close and encouraged the families to invite each other for meals.
I suppose individual circumstances vary and each family/couple must use their seichel when inviting company.
(Perhaps things were different when I was a teenager/newly married 15-20 years ago.)