You feel bored or sleepy with them
Ten minutes into their account of something that should matter (a divorce, a failing project) you're fighting to stay awake.
Rule out first
Your own tiredness or low blood sugar. A topic that genuinely doesn't concern you. You're preoccupied with something else.
What could explain it
Countertransference: The boredom is specific to them: you're alert with others in the same meeting, and it lifts when you name what's going on.
Intellectualisation: They're talking about feelings without any in the voice; you're bored by the absence of the person.
Schizoid personality: They keep you at arm's length; there's no contact to be had, so the room goes dead.
Persistent depressive disorder (dysthymia): Their low energy fills the room; you feel heavy, slowed and a bit hopeless too.
Passive aggression: Something angry is being withheld; the flatness feels effortful, and the boredom has an edge of irritation.
I–It (Buber): You feel like furniture: they talk at you, not to you, and anyone could be in your chair. The boredom is what being used as an audience feels like.
A next move
Interrupt gently and ask how they feel about what they're describing. If you wake up, the boredom was the defence; if they stay distant, it's their style; if anger appears, it was withheld.
If it’s you
What am I not feeling with them that I would expect to feel?