Huh, I always figured it’s because it’s one of the masculine-conforming reasons to have a friend take a nice photo of just one guy. Single guys with plenty of friends go out and do stuff together, but you don’t take well-lit, posed photos by yourself normally. You might take a group shot, but then you risk looking small or ugly next to a more attractive friend. A posed photo of a guy by himself looking good is going to look like it was taken by a significant other.

It also says “I like to fish, and when we are in a relationship, I expect to continue to go fishing with my friends.”