Best part of this article for sure!
Don't worry. You're so funny and smart and amazing, any girl but me would be lucky to date you. You'll find someone, I know it. And when you do, I'll be right by your side to suddenly become all flirty and affectionate with you in front of her, until she grows jealous and won't believe it when you say we're just friends. But when she dumps you, that's just what we'll be.
Best friends. Friends forever.
***
And also, if OPs BFF isn't the flirty affectionate type, then guaranteed she is the type that someone else alluded to...the one that is very very subtle about her possession of his time when talking to new girlfriend. She will be sure to drop into conversation how well she knows him, that X is his fav song and "don't you remember that time we went to that one restaurant...." laugh laugh laugh....awkward look "oh...it's sort of an inside joke thing"
Don't feel too badly, OP...guys often just do not have any clue about the type of sneaky and subtle jabs that girls use to claim their territory all while being oh-so-friendly to new girlfriend. You may just be completely clueless about it. And it will be the BFF who gives you the doe-eyed shrug and "I don't know why she has an issue with me?..." But...she knows. She knows, OP.