Zenitsu has actually been in a few relationships although due to his nature, Zenitsu is kind of.. blindly trusting when it comes to love

Beacuse of this doesn't have the best track record, But he’s the love at first sight person.

So the first instance you showed kindness to him he knew he was done for

Of course, he automatically asked you to marry him, and started babbling about how he would probably die soon.

S-s-so like we should g-get m-married!