I'm tearing my hair out here. 7YO DS has just finished another disastrous playdate where he just didn't want to share any of his toys. His poor friend was saying 'Well how about this instead then?' but just got no after no after no. DS shut himself in his room in tears/frustration/anger, literally clutching this toys to him, while the friend looked on in bafflement. This happens with pretty much every playdate apart from with his best friend - I suspect because his best friend is very gentle and compliant and basically goes along with anything DS wants to do.
I've tried to talk calmly with him, both outside of playdates and during them, i.e. in today's situation, to find out what's bothering him and try to find compromises. He always says he doesn't want them to get lost or broken (neither of these things have ever actually happened with friends) or to have to clear up the mess afterwards - I tell him every time that I will help with this. I get that it's somehow a control thing and have suggested things like, well you choose a selection of things that you can both play with and put others ('precious' things) aside, or you take turns to choose what you play, but it always gets to the point where literally everything is out of bounds and he will only ever agree to something he wants to do.
Getting cross and trying to force the issue is pointless - once or twice I've got frustrated and ended up doing this but of course it doesn't work. I just don't know what the solution might be - it's understandable at age 2 or 3 or 4, when they're still little and have trouble sharing, but he's 7.5 now and things show no sign of improving. He's not an only child (his sister is 11) and he's absolutely fine at friends' houses - I always get nice feedback about his behaviour - but of course that's because it's not his toys/things being played with. Any suggestions for help would be so much appreciated, as it's hugely stressful - both for me and for him, and obviously no fun for the poor kid who's visiting either!