It's where you have to stay at home for 40 days, because French for 40 is quarante. But it's mistaken by idiots who think quarantine is another word for coronavirus.
Me: What does quarantine mean?
Nerd: Coronavirus!
Me: No, it means where you have to stay at home for 40 days.
Nerd: You patronising smartass, you are dumb.
Me: You are dumb with nerd glasses on, but maybe you know a lot about algorithms.
When someone comes on extremely strong with early declarations of love or possibly a future relationship together. The purpose of this is to gain confidence in order to make someone comfortable enough to eventually break quarantine and have sex with them.
(Original Source: Unzippedintentions.com)
"He told me that he could totally see a future with me and see himself falling in love. I think he's Quarantine Grooming me"