There was an interesting article in the Globe & Mail recently that posed the question "How soon is too soon?" Apparently comedian Patton Oswalt is coming under fire for getting engaged (and then remarrying) a little more than a year after the sudden death of his wife at age 46.
There doesn't appear to be a concrete answer to the "how soon?" question, but if you cross that line, you'll probably hear about it...!
And yet... I keep thinking the people who are crying "too soon!" about adults acquiring a new partner/spouse are probably the very same people who would tell parents who have just suffered a miscarriage or stillbirth, "You can always have another baby" or "The best thing you can do is to get back on the horse (!) & have another baby as soon as possible." (This used to be -- and might still be, for all I know -- common post-loss advice from doctors, nevermind your mother or best friend or neighbour.) Right?