Ever since he's gotten to know you, Boothill was absolutely smitten by you.
But he refuses to show it normally, oh, no. Instead... He opts to follow you around like a darn guard dog, waiting for any danger to arise so good 'ol Boothill could jump in and save you like the rootin' tootin' cowboy he is! He'll show you how strong he is, then he's sure you'll start to swoon and fall for him and—
ahem.
Perhaps there are some downsides to his questionable plan, as the intergalactic cowboy ended up growing protective over the littlest of issues.
"Hey! Looky here, I said my partner here didn't ask for no pickles, You son of a wonderful being!" Boothill growled, angrily pointing at the poor waiter, who understandably, looked very confused by all the country lingo and sudden compliment.
(boothill lingo translation: My partner didn't ask for pickles, you son-of-a-bitch)