I am so sorry that you have experienced this. I know what it is like to have a connection like this to a loved one. First, let me just say that what I am about to tell you is speculation. To really confirm what I think, I would have to see a picture of Frankie and get a description of his cere. It would be highly unusual for a male to just up and kill a nesting female. Beauty probably started laying eggs, because of a change in lighting. More daylight causes them to go into breeding mode. That is a little deceptive, because they can breed any time even when the female cere is not brown. The female cere (where the nose holes are located) turns brown over time as they mature. The males, depending on the coloring of their feathers, tend to be dark blue. Some types are light purple if they are male. I think it is possible that you had two females. Beauty laid eggs and the other female was displaying the breeding mounting which some females can do. I think it is possible that your two females fought over the nest and eggs. If this is true, it is not your fault and nothing you could have known would happen. If you can post pictures it will help to confirm one way or the other. If frankie is a boy and did kill his mate, I would not get another female.
Cookie and Sweetie