My brother-in-law is a cop. One of his good friends was killed while on duty. His young wife went on to marry another cop who was also a friend of her deceased husband. One of the young guys who worked for my husband was killed in a car accident and his wife married another sailor that was a close friend of her husband. As you said, it happens all the time and I don't think there is anything wrong with it.
I agree that there's nothing wrong with it. I'm also shocked by some of the posts in this thread. Even if people don't like it, it's really none of their business.