My colleague vents to me every day. How do I stop being his daily debrief?

I said, “That sounds frustrating,” and my lunch disappeared into another forty-minute account of what our manager had done.

My colleague and I used to chat about everything. Recently, most conversations have become a replay of his meetings, messages and disagreements at work. Some complaints sound reasonable. Others are hard to judge because I wasn’t there.

I keep listening because I don’t want to brush him off. I’ve also started delaying my break so we don’t leave the desks together, which feels less kind than saying something honestly.

He hasn’t asked me to solve the problems. When I suggest speaking to the manager, he says he just needs to vent.

How would you make room for the friendship without agreeing to a daily debrief? Is it fair to say I need lunch to be about something else, even when he’s having a difficult week?