“People should spend time with their families, and that’s it. There’s no reason to socialize with anyone who is not your family.”
That’s not frumkeit.
Have you ever benefited from a family with an “open door” policy? I guess when you learned in E”Y you never ate by anyone, and I assume you have never opened your door and heart to someone who needed a warm meal or a listening ear. There’s a lot of space between young couples inviting each other to socialize, and “people should spend time with their families, and that’s it”.
Nuance is an important word.