Partnership is under threat in some organisations because managers are taking its benefits for granted and reverting to type, the Involvement and Participation Association's chairman Willy Coupar told delegates.
Some organisations are looking to discard partnership, having "pocketed the benefits", Coupar said.
"There are indications that when things are getting a bit difficult, people on the board are questioning it and saying, 'Should we not be getting rid of this because this is costing us money? Let's start playing hard guy again.'"
The IPA is a voluntary consultancy that helps employers and unions work together.
Coupar's comments come just weeks after the 10-year-long partnership deal at utility Hyder came close to collapse. The company made a surprise announcement of 1,000 redundancies, prompting a threat by Unison to ballot for strike action if any severances were compulsory.
Austin Ballingall, AEEU shop steward at Southampton Container Terminals, said maintaining partnership is just as challenging as establishing it.
"Things have been difficult and it is very easy to slip into confrontation over something. I believe partnership is the only way forward but you have to keep it going, and that is hard work.
"Many times people are too ready to get up and leave the table but you have got to sit down and talk. There has to be responsibility on both sides."
Peter Scanlon, HR support manager at Littlewoods, said it is important that everyone involved in a partnership recognises the pressure others are working under.
"I think management needs to recognise the almost evangelical attitude of some union reps towards partnership and the fact that they are in some cases being harangued by other members of their union for this approach," Scanlon said.