Sorry you guys, but it means what I said in the first answer. Check out the "but" connecting the two phrases. In addition, there is a sarcastic tone in the sentence structure. The guy really is bothered that the other person does not feel heartbroken. Why make a song about it otherwise? Congratulations, Tania, for spotting it! A similar example. You show up unannounced at a friend's place. He says: "It's not as if I mind you showing up unannounced like this." I assure you, he is not happy with you.

"it's not as if I mind that your heart ain't exactly breaking." means I don't care that your heart is not breaking. these are all the same: "it's not as if i mind" = It's not like I don't mind. = I don't mind = I don't care. "not exactly breaking" --- It means "not quite". It means his heart is not breaking, and she knows it. This is a pattern used in colloquial English. "isn't exactly" means something is not quite like something else. It's kind of an understatement or a euphemism. It's hard to explain, but I think if i give some examples you will understand quite easily the meaning: the pattern is always: "(something) is not exactly (something else)" and it means that, something is definitely not something else. Your heart is not exactly breaking -- this really means that your heart isn't really breaking, or isn't breaking at all. there is a pattern in spoken english which is: " It's not exactly ___, but I'll take it ! " it means, it's not quite like ___, but I will accept it anyway! example: Q: Do you like this painting? A: Well, it's not exactly "fine art", but i still like it.

Actually, it is not as Eliot says. The speaker is saying that he does not mind, and that the other person's heart is not breaking. The speaker was not in love in the first place, so he doesn't care that the other person is not hurt. It is a complicated sentence.

这并不表明我在意你是否心碎..是有点怪

The guy is a little upset that the other person is not heartbroken. It's kind of weird, but yeah.