Loners

let me see if I can put this together.

She, possibly, was flirting with you? Check.

When you make it clear you're married, she counters by referencing some "perceived suggestive comments" you uttered? Check.

She then finally unfriends you under a dubious excuse? Check.

Then you post “And I’mmmmmmm already gone” to her post and she freaks out? Check. Check.

I could be totally off on this but my initial guess is she thought you were using the song lyrics to taunt her with your unavailability, “And I’mmmmmmm already gone”, being taken as a "Ha Ha. You can't have me." If she was seriously flirting, the rebuff might have pissed her off. And if it was just friend flirting, she might have been concerned about it being taken as a serious gesture on her part, inviting all sorts of conclusions about her. Either way, the purpose of quietly un-friending you may have been intended as insurance against unflattering interpretations of her motivations toward you. In other words, you can't be accused of being attracted to someone you've un-friended.

She may have been hyper-sensitive to giving unrequited gestures, whether intended or unintended, and “And I’mmmmmmm already gone” was the trigger.