Asked by Wiki User. They started dating in the episode-"Rules of Engagment" which is in the third season, episode They aren't dating. Cause your so fat. The Memories in the Shallow Grave.
Top 10 Santana & Brittany Glee Musical Numbers
Brittany Pierce - Wikipedia
They began dating in the season two episode Comeback. There had been no mention of a breakup between these two on the show leaving some viewers confused. It is most likely that they broke up prior to the episode Born This Way because, in that episode, Santana starts "dating" having a false relationship with through blackmail to try and win Prom Queen Dave Karofsky to which Sam does not object, though he seemed sour when it was first revealed. In Duets, Sam is introducted to New Directions. After he introduces himself, Santana finds herself unimpressed saying to him that "he has no game" leaving Sam unimpressed. Santana along with Quinn and Brittany flirtatiously and playfully joke about Sam's abs, admiring them. Brittany says she can't wait to see Sam in his Rocky Horror outfit as it is shirtless.
Santana is assertive, ambitious and insecure. Santana sometimes acts a bit like a bully towards the other members of the Glee Club to feel better about herself. At her best, Santana is caring and compassionate towards other people, especially in her relationship with Brittany. She also becomes nicer to Rachel and Kurt.
Glee was one of those shows that managed to create some of the most lovable and yet at times infuriating characters in the history of television. Santana is, arguably, one of the best characters to have ever appeared on the show. One of the things that was always truly astonishing about Santana was how adept she was at adapting to various musical styles and genres. This is one of those songs that seems to have been made for Santana.