Getting turned off when someone tries to 'steal' your favorite character

Ok this is kinda an immature post but I've seen lots of people experience this before so like, how do I (genuinely) stop myself from getting turned off and wanting to drop the character I like when someone else tries to compete with me for them? Like, I just shared my new fav character on our group and someone said "No he's mine" And I just felt all interest drain from my body. I'm aware that I shouldn't be so bothered since it's inevitable other people like them as well but pls give me tips or something so I can get over this feeling bc I hate feeling this immature and stupid.