i call it the fetish demarcation line (FDL). maturity isn't determined about whether you have a fetish or not; maturity is determined by how you act when someone else is talking about a topic, and you are on the opposite side of the FDL from them about said topic
like if you have a plane fetish and you are talking to someone who doesn't have a plane fetish, and they're just interested in planes, are you gonna make it weird for them? are you gonna make it uncomfortable? or are you gonna be a grownup about it and learn to respect their boundaries about it?
or if you enjoy dragons in like a fantasy/fairy tale sensibility, and you encounter someone who clearly just wants to suck and fuck them. are you gonna deride and make fun of them, or are you just gonna be a grownup about it and respect that they're into something in a different way than you are, and leave it at that?
you're gonna find yourself on the opposite side of the FDL as someone. it's a guarantee. so be sure to establish boundaries early and try to respect that people like things for different reasons. be a grownup about it