Kristin Cavallari has a new — much younger — man in her life. The “Laguna Beach” alum, 37, debuted her romance with 24-year-old model Mark Estes in a Tuesday Instagram post.

Reality TV star Kristin Cavallari is known for her years on MTV ... Estes is also a designer and model, as seen below for the Montana-made fashion label Belmont Acres Clothing, of which is ...