I wish my girlfriend would stop asking to borrow my vape?
That's odd, why don't you want your girlfriend to borrow your vape?
I want to vape with my friends
I get that you want to vape with your friends, but it would be nice if you let your girlfriend borrow your vape. Partners are supposed to be generous with their belongings, and I'm sure your girlfriend would appreciate it.
Why should I? I'm the one who bought it.
You're right that it is your property and you can share it or not share it with whoever you want, but most people would assume that you'd be okay with sharing things with your girlfriend.