May 2019 - last edited May 2019
My kid had a wish to "have a sleepover", I promised him to fulfill it.
Then he grew up to teenager, invited a friend which agreed on staying the night, but after that the whim was still there - not fulfilled.
May 2019
@krecha_ae The sleepover wish is kind of borked anyway, in that it doesn't always read as fulfilled when it should, and it's hard to make guests stay the night even after they've accepted the invitation. (These two things may be related, or not; there are plenty of bugs that never got fixed.) Here though, I think the problem is that a child sleepover is not the same "event" as one for teenagers, so your sim can no longer fulfill it.
Given how hard it can be to complete this wish, and how few points it grants, I tend to skip this one anyway. At this point, it's probably best to cancel the wish entirely.
May 2019
I tried to fullfill this wish by two kids (not teenagers), and it's the same - it does not have effect (at least when other sim was sleeping at my family's house).