Is it normal i look at photos of my bf many times a day?

When I'm not with my bf throughout the day I look at the photos of us we have together. Depending on how busy I am that day, sometimes 5 or 6 times, each time lasting for only a min or so; then other times each time lasts about 10-15 minutes. My sister has walked in on me just staring at photos of him, I know it's probably not healthy but I just miss him so much when we're apart and he's so handsome. I'll do it even if I was just hanging out with him earlier that day.