You have a couple options. You can continue to enjoy the flirting but hold on to your heart so you don’t wind up with dashed hopes. Or you can step back and convince yourself that it’s not worth crushing on someone who is taken yet pays a lot of attention to someone else—you. Most school relationships don’t last forever, so it’s possible he’ll move on and all this low-key flirtation will blossom into something later. But be careful what you wish for because, chances are, he may always be the kind of boyfriend who keeps his eyes open for the next romance.