The Dane is being linked with PSG.
Trundle told talkSPORT: "The recent events have been surprising because he's been very successful, enjoyed a brilliant season and you'd think everything was good in the Swans camp.
"But no-one knows what goes on behind closed doors and for talks to break down something's gone wrong. I know the chairman reasonably well and talks wouldn't break down for nothing.
"After the season (Laudrup) he has had he should be happy and want to progress again.
"And I think it's very important to keep hold of him. It's been remarkable what they've done, with league position and the cup win, and I think every Swans fan will want to hang onto him."