Could the key to a lasting relationship lots of intimacy?! Based off of Brittany Cartwright’s experience in the love department — or lack there of — it seems to be of high importance. The Vanderpump Rules star recently revealed a drastic decrease in intercourse was one of the main reasons fueling her marital demise to estranged husband, Jax Taylor. “When Jax and I first met, it was awesome. We were having s– all the time, 24/7, and I mean, we didn’t miss a day,” the 35-year-old admitted in a confessional interview during the Tuesday, April 9, episode of The Valley. “And then, it has just chan…