When you are so pissed at your significant other that you do everything you can to ignore them for a week or longer, but you are too damnlazy to leave or move out. (It's like a twenty four hour ice, but longer.)
After working all damn day and doing the dishes after dinner, my lazy-ass old woman bitched at me for not cleaning the fucking spoon rest. So I took a week long relation staycation. I fucking hate moving.
When the vibe/mood/aura of a room/place seems uneasy and out of the ordinary, the air is heavy and something feels wrong. It commonly foreshadows that something terrible is about to happen.
The term was heavily popularized in 2017 when the game DDLC (Doki Doki Literature Club) was released, and one of the characters (Yuri) uses it.
“Stagnating air is common foreshadowing that something terrible is about to happen” -Yuri 2017