Aaron Carter broke up with his girlfriend days before announcing he's bisexual -- and it seems the news might have pushed things over the edge ... TMZ has learned.

A source close to Aaron tells us he and now ex-GF, Madison Parker, broke up sometime last week ... and that it was a long time coming.

His rep tells TMZ the decision was mutual, and Aaron and Madison "love each other and respect one another dearly." The rep also adds ... Aaron's personal statement speaks for itself. He's hoping to refocus his attention on his music.

As we reported ... Aaron announced Saturday night that he's found both men and women attractive since a young age. It's interesting -- we caught Aaron and Madison -- whom he referred to as his girlfriend -- driving around L.A. together early last week ... right after he apparently got out of surgery

A LITTLE OUT OF IT
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