I had with my Best Female Friend...?

it only happened once...not a pionate thing just ****** but she acts different now...we completely agreed to the pretend it never happened rule (she is still trying to get her ex back) I am fine with that but she still acts weird sometimes any advice on how to get our platonic friendship back the way it was...we used ot be able to change infront of each other joke about anything...were still close but i want my old friend back...