It's a running gag among Swifties now -- anytime she steps out into the spotlight, especially on a night like this, Alwyn starts to trend on Twitter ... and the same question is asked by literally thousands of users who get a look at their icon ... CAN YOU FIGHT???

Of course, they're all kidding ... but it's still pretty funny. You could argue they're asking because they wanna make sure JA can fend off any would-be punks in the street. That, or they're wondering if he could possibly take them on if they wanted TayTay for themselves.

A little toxic, but hey ... that's the what comes with a diehard following these days. 😄

As for Joe himself, he was nowhere to be seen as Taylor walked the red carpet in a sweet-looking blue dress. He hardly shows up for these things anyway -- and even more rarely appears with Taylor at all in public. That's not to say they aren't together ... 'cause they are.

You'll recall ... she was just spotted out with Joe back in October of last year during a nice day in NYC -- and earlier that same summer, the two of them were seen cozying up on a romantic vacation in the Bahamas ... where they looked very much in love in the water.

Keep in mind ... she's been dating this guy -- a relatively low key British actor -- since at least 2017. So, they've been going strong for a minute now ... breaking past their 30s together.