What happend during sex

Hi everyone i would like to ask something that happend to me.
We were having sex with my girlfriend she uses birth control. What happend was i was on the edge when i pull out and wait coupe of secconds and then continue, but this time when i pulled out i had that feeling you get after an orgasm but i did not cum and i went soft. What could happened i never never experience this…. Could anyone help ? or clarify
Thank you everyone