I Pranked My Sister's Boyfriend for Too Long and It Went Badly

Okay, so I think everyone has a little prankster in them, right? Well, mine is pretty big. A few months ago, my sister invited her boyfriend over to our family house for the weekend. I just couldn't help myself, my first thought was to play one of those practical jokes you buy online. You know, the kind that involves fake spiders and exploding pens. So, without telling anyone else in the house (because they'd probably have stopped me), I went ahead with a harmless little prank: a box labeled 'Gift' that when opened had an air horn inside instead. It started out okay; he seemed surprised but laughed it off. The thing is, though, my sister has always joked around about how he can be kind of gullible and easily led to believe something crazy. I thought maybe this would just add another funny story to their relationship. But as the weekend went on, every time we'd get together, I'd come up with a new joke for him. The turning point was when I set off one of those smoke bombs in the kitchen while he was making dinner. It wasn't malicious or anything; it was just another stupid prank to add to our collection of family stories. But the way things played out, it got too dark in there and we couldn't find the light switch, everyone freaked out, my sister yelled at me, and her boyfriend had this look on his face like he didn't know whether to laugh or be mad. It's been a few weeks since then, and I haven't seen him around. When I do see my sister now, she won’t even make eye contact with me. At first, I thought it was just the aftermath of something that happened before this weekend, but when I mention anything about her boyfriend, there’s always an icy silence. I’m starting to wonder if maybe, despite how silly and harmless it all seemed at the time, my pranks actually crossed a line. Now I'm left here, trying to figure out if I should just wait for things to blow over or if I need to go make some sort of apology. What did I do wrong, really? Did he not take them as jokes and is now wary of her? Or was it all in my head, and she's mad at me for a different reason? It’s driving me crazy thinking about it.