

I like the in-universe swears from some of Brandon Sanderson’s fantasy novels: Rust (rusting, rusted) and storms (storming) come to mind.
A québecoise roommate of mine got her whole office yelling “chicken FRITE” (fried chicken in franglais).
“What the shoes” is kind a fun one. I’ll also yell “fudge knuckles!” which doesn’t really mean anything but is pretty satisfying to say.
Crushes are like the common cold, I think. Sometimes they appear out of nowhere, and we have to endure them until they pass, but we don’t have to indulge them.
Something that can help is to pick something that’s an annoyance about that person, or a reason that you wouldn’t actually want to be with them, and redirect your thoughts toward that when you find yourself thinking of them. It can be something really important (“No; I could never be with a married man!”) or even something very dumb or superficial (“Ugh, hairy ears!”). It doesn’t really matter, as long as it’s something that helps to train your mind/heart away from “I want” and towards “I don’t want.”
If you know you can’t be with someone, or wouldn’t really want to outside of whatever fantasy you’re indulging, then finding ways to stop indulging in that romantic daydream is the best thing for both you and them.
Edit: something else to ask yourself is whether this is actually about this man, or about something he’s come to represent to you. You’re a long way from home in a foreign culture. Are you really looking for his love, or are you craving something he represents (stability, home life, end of loneliness, etc.)? It’s worth reflecting on.