Sibling being weird about me liking the same character

So I've started playing Date Everything, because I consider myself to be completely fictosexual. It kinda feels like dating culture for me, as someone who feels little to no interest of any kind in real people. The problem is...my older sibling has been like, "Hey, plz don't be obsessed with this character because I think they're my favorite". And I'm just like "Okay??" fully planning on obsessing over whatever the hell character I want, just not talking about it to them. And for some reason they've been like...oddly insistent about it. Which frustrates me. They're currently doing dating culture irl, because real people do it for them. Meanwhile, the closest thing I have to scratch that itch is a game we both happen to like. Hell, I don't even like 90% of dating sims! Like...this is all I have. Why can't you just let me have this without making it weird?

Anyone else experience oddly judgemental crap like this?