I found out my sister’s “new boyfriend” is my old teacher.

I honestly don’t even know how to process this. My sister (she’s 23) just told me she’s dating someone new, she seemed super happy and secretive about it for weeks. When she finally showed me a picture… my stomach dropped. It’s my old high school English teacher.

He’s in his late 40s. He taught me for two years. Back then, he was the kind of teacher everyone liked, charming, funny, a little too friendly at times, but no one thought much of it. Now seeing him with my sister feels off.

I don’t know what to do. I don’t want to ruin her happiness, but I can’t shake this weird feeling. It’s not just the age gap, it’s the fact that he knew me when I was a teenager. He’s been in our family’s orbit before, and now he’s dating my sister?

If I tell her how I feel, she’ll think I’m jealous or being dramatic. But if I stay quiet, I feel like I’m letting something wrong slide.

What do I even do with this?