to expect children to stay around when you give in to their request to play with them?

[LetTheRiverAnswer]

Something like this: child appears holding a jigsaw puzzle box begging me to do it with them. I explain its a very big jigsaw, but no, no other jigsaw will possibly do. It can not wait. We tip out all the pieces. Child wanders off. Comes back every so often to check I am actually doing the jigsaw puzzle. Shocked to the core when they discover I'm not. Do they just think I'm looking bored and need entertaining? Or want me to play until they remember I'm not as fun as they thought?

Hahahaha. I get this a lot where DD gets so wrapped up in her fantasy play that she leaves the room and when she comes back in is cross to find me mucking about on the iPad.

Hahaha!! This hasn't happend to me yet as ds is only one and very definite that I am to join in all his games. Am actually slightly looking forward to the day he wanders away from me! When will that be?

DS (4yo) does this at soft play. "Come in the slide with me, come on the slide with me, come on the slide with me" over and over. So I go with him. We climb right to the top of the massive play frame, through all the nets and ramps and switch backs, and that's when I realise he's buggered off and I've instantly morphed from 'mother playing with her son' into 'weird 32yo woman lurking alone in the playframe'.

DS1 (2.5yrs) tends to go more for the "Come and play!" and when you do - no. We're not to touch the toys. We have to stand / sit there and admiringly watch DS1 play with the toys.

He gets very cross when I decide to go off and do something else.

My daughter is 3 and does this. She gets so upset when she discovers that we're not playing where she left us.

All of those sound familiar! Glad I'm in good company
I also like the "come and play train set" invitation. I get to lay the track, but not like that. And then push a train around, but not like that. Not as tempting as he seems to think it is.
Seems to be a three year old thing.