Did the couple expect that their social life would change dramatically after having a child, or did they expect things to stay the same?
I've known people who fell into the latter category (even after being repeatedly told "no, really, things are going to change and you won't be able to do all the things you used to do). Reality ended up being harsh for them.
I'd just like to voice my experience on this matter. Having Little Knit did not significantly impact my social life. Having a baby does not have to change everything. It does if you let it, but babies are remarkably adaptable and it doesn't have to.
I'll give two real examples of two friends who had kids before me.
Marissa was the first friend in our group to have a baby. Things like movies, of course, stopped for a little while in the first year. But her husband Brad still came out with the group for those. Our games nights continued as normal. There was no need for hushed voices. They decided in the early days not to go around whispering when Lina slept so that she would learn to sleep through noise. And she did. Trips to retaurants involved bringing Lina along in her carseat. She would quietly sleep. Later, she would sit on Marissa's lap or cuddle up in a wrap. Now, at 4, she can sit quietly in a restaurant and behave herself, and has been able to since she was old enough to sit up. It's just a part of her life. None of us changed and because Marissa and Brad were so easy going, we were all perfectly happy to accomodate their occasional
requests to do things differently.
Duala also had a baby a short while later. She did things very differently from Marissa. Neither she nor her husband continued going to the movies. If one couldn't go, the other wouldn't. After bedtime, no one was allowed to speak above a low voice. She thought it was abominably selfish to bring little Leslie out to a restaurant, even if Leslie was sleeping. (Incidentally, at 3 almost 4, Leslie cannot sit still at a restaurant.) Getting together with them was always on their terms. After a while, their friends started dropping them from activities.
It was the attitude, not the child.
As a side note, I opted for Marissa's approach and slotted Little Knit into my life rather than making lots of changes and I have found myself much happier for it. Of course, I modified things to an extent, but never expected others to make changes. As a result, my social life is not extremely different now than it was before LK came along. Edited, as I just realized I mixed up the ages of Marissa and Duala's kids.