AITA for refusing to share my homemade meals with my roommate’s boyfriend?

So I (25F) have a roommate, Sara (26F), who recently started dating this guy, Tom (28M). I cook most of my meals from scratch because I enjoy it, and it’s cheaper and healthier for me. Sara’s fine with it and occasionally I’ll share leftovers with her when I make extra, no problem.

Lately, though, Tom has started coming over more often—almost daily—and has been helping himself to my food. He doesn’t ask, doesn’t offer to contribute groceries, and never says thank you. I didn’t say anything at first because I didn’t want to be rude, but last week I came home to find he’d eaten an entire portion of food I’d prepped for my next day’s lunch.

I finally confronted Sara about it and said I didn’t appreciate Tom eating my food. She brushed it off, saying he’s just “comfortable here” and that it’s “not a big deal.” I told her it is a big deal because I budget and plan my meals, and if he’s eating my food, it throws everything off. I made it clear I wouldn’t be sharing anymore, and I asked her to let Tom know.

Fast forward to yesterday—I made a pot of chili, and Tom came over while I was out. When I got back, a big chunk of it was gone. I was furious and told Sara that this was exactly what I was talking about, and it needed to stop. Sara said I was overreacting and called me “stingy” for not sharing food when it’s “just a couple of bites” (spoiler: it’s not). I told her I’m not her boyfriend’s chef and that I don’t owe him free meals.

Now things are tense, and Sara’s acting like I’m the bad guy here. Tom hasn’t said anything directly, but I can tell Sara told him because he’s been giving me the cold shoulder. I’m starting to feel guilty, but I don’t think I’m wrong for wanting boundaries here. AITA?