This really, really sounds like a song about being trans to me, specifically about being a trans woman or maybe genderfluid - your social identity is as a boy, and you feel like people love you because of that identity, but internally, there's a girl that you feel like you have to keep secret, but you also don't want to hurt her or get rid of her because she's also you. So you're conflicted because if you come out, you're getting rid of this male identity that you don't necessarily hate, but that does hurt, and you can't take it back if you do come out. You know you'd risk losing the love your family feels for you, and the social identity that you're accepted for, and that there would be shame and consequences if you came out. But staying closeted is deeply painful, so you're "on the border" or on the fence about whether to come out, all while continuing to deny it if anyone sees her.
This really, really sounds like a song about being trans to me, specifically about being a trans woman or maybe genderfluid - your social identity is as a boy, and you feel like people love you because of that identity, but internally, there's a girl that you feel like you have to keep secret, but you also don't want to hurt her or get rid of her because she's also you. So you're conflicted because if you come out, you're getting rid of this male identity that you don't necessarily hate, but that does hurt, and you can't take it back if you do come out. You know you'd risk losing the love your family feels for you, and the social identity that you're accepted for, and that there would be shame and consequences if you came out. But staying closeted is deeply painful, so you're "on the border" or on the fence about whether to come out, all while continuing to deny it if anyone sees her.