Chris Brown -- Karrueche Loves Me Not ... She Loves Me

Chris Brown and Karrueche Tran prove ... there really is a fine line between love and hate ... because it seems they're back together.

They two got super handsy Saturday at a charity football game in L.A.

Just days ago Karrueche had nothing but bad things to say about Chris -- and sources close to Brown painted an equally unflattering pic of the relationship.

We also got the former couple leaving the game ... and once again, Chris was openly affectionate.

Michael and Nicole, Justin and Selena, Chris and Karrueche ... maybe this is the secret to a long relationship.