As others have indicated, your job in this situation is as a very interested observer.  You have no say in the matter, even if you do have an opinion, you need to keep it to yourself.  He's an adult, you've done all the raisin' you're going to do.  All you can do at this point is be friendly, cordial, and supportive and pray that he and she are both happy no matter the outcome.  Good luck to all concerned.