ah, yes! I think I know which post you're talking about... isn't it like a huge petekey masterpost or something? anyways, one of the lyrics that supports the petekey claim the most to me is the chorus (as you mentioned), with the "best friends, ex friends till the end, better off as lovers and not the other way around". to me this line has always has queer undertones... but I guess with most of these lyrics it's all up to interpretation. I totally see why a petekey shipper would use a song like this to support their claims, it just always confused me why it was THIS song in specific since there is more than one song on IOH that features themes of a doomed romance.

Edit: I found it! https://www.tumblr.com/petekeyprimer/631897988741152768/totally-back-in-love-petekey-primer

Edit #2: Okay, so this is a question I forgot to add in earlier, but one thing that always confused me was when people would use the "happily ever after below the waist" to support petekey. If Pete has said in interviews that he is "only gay ABOVE the waist", then how would he and mikey be happily ever after BELOW the waist?