Any Facebook experts around - how could this happen?

[IWillAlwaysBeinaClubWithYouin1973]

I use Facebook a lot on my laptop. Last night I thought I logged off, and then this morning when I got up I opened up laptop and it was logged in to Facebook, showing DD23's boyfriend's home page. Only I never searched for him - I never knew his surname and she's not been seeing him that long. Only DD21 and I live here, no one else. DD23 has her own place.

I've asked DD21 if she got up in the night and used my laptop, she says no. I told her what I'd seen and she was quite adamant that she didn't search in Facebook to find this guy. I've gone onto the activity log and for some reason it only shows up to the time I went to bed last night (which was past midnight so showing 31st December).

Either DD21 did get up and use the search facility (in which case she would have had access to all my Messenger messages too which is a big worry as I write a LOT of personal stuff to a couple of close friends) or its the most bizarre coincidence and I can't see how it can be explained. Yes I knew this boyfriend of DD23 existed, but I never searched for his profile page or anything about him. And how come no "activity" is logged from the time I went to bed after might night, until the time I logged in again 11am this morning? Is there a different way I can check activity of any sort? (Edited to say its not appearing in my laptop history either - DD21 struggles with tech so I don't think she'd know how to clear the history)

Regardless, you want to put a password on your laptop that nobody else knows. If someone else needs to use your laptop, have a guest account set up for that.
Years ago I learned that the hard way as the cleaner went on my laptop and (not realising she wasn't logged into her account) friended various people I then had to unfriend. Yay. Password after that! No leaving it unlocked...

Not sure… but I had a weird FB thing recently, in the form of a friend request from the wife of my high school maths teacher (who later became a colleague- we connected online in that era, not as a pupil!).

I hadn’t even realised I was still friends with him on Facebook until a few days before the friend request, when he popped up on my feed in some pictures from a mutual friends wedding. I had a look at the snaps, thought to myself how he was aging far better than I am / how grown up his daughters were, and went on my merry way. Didn’t interact with any of the pics, didn’t message etc. checked my history and there was no registered activity- so his wife wouldn’t have a “reason” to connect with me.

Still not sure why she added me on Facebook. Can only assume bug in the machine.

Accidentally clicked on him in the 'people you might know' thing that always likes to appear with ex-boyfriends and other people from previous lives when you were shutting down.

Seems like the most likely explanation.

Presumably you're all on the same wifi network and / or use your phones / tablets etc in proximity. I get my sibling's boss pop up on my feed when we've been together. My sibling isn't an FB friend, so it can only be that we've been on the same network and the cookies have picked that up.

Thanks all - I asked DD23 the one with the boyfriend (!) and she too suggested it probably came up in the "people you might know" section and somehow I clicked on it. I'm going to let it lie and change the passwords!