Hailey Bieber couldn't contain her love for her husband Justin Bieber when she celebrated their four-year wedding anniversary on Tuesday.The 25-year-old model gushed that the pop superstar, 28, was the 'love of my life' in a sweet Instagram post marking the occasion.Hailey shared several photos of the lovebirds kissing, including a photo apparently snapped on their wedding day. Still going strong: Hailey Bieber, 25, marked four years of marriage to her husband Justin Bieber, 28, in a sweet Instagram post from TuesdayThe blond beauty wore her elegant white gown in the photo as a suited-up Justin leaned in to kiss her while holding her hands down at his sides.In addition to her white train, she had another sheer layer attached to her veil that was spread out even farther on the lawn and had 'Till death do us part' embroidered on it. She captioned her photo: '4 years married to you.