Kristen Doute is headed for the altar with Luke Broderick. RadarOnline.com can reveal the reality star, 41, was stunned when her boyfriend of two years popped the question during a romantic boat ride in Hawaii. Doute confirmed the news with a photo on Instagram showing Broderick down on one knee against a tropical sunset backdrop. She wrote in the caption: “[I]’m wrapped around your finger like this ring [I]’m wearing…out of the all the fish in the sea, you chose me”. Broderick told Doute to watch for dolphins as he got down on one knee and presented a “4.27 carat Emerald cut diamond, plus a…