You have the right attitude, you can't change the future. His choice remains to be you so be happy. We seem to expect love to be "permanent" and life long. They may not be capable of that with anyone and all we can do is sweep our side of the street to set a good example. Lead by example in everything in your R.
I was sick as a dog yesterday and W was very compassionate. She had a terrible day yesterday so I massaged her to sleep and did it again this morning to let her know I was there for her. The R is still the same, status unknown. It bothers me about 15 minutes a day but the rest of the time I am fine. I fight the same battles as everyone else but I don't dwell on it any more. I do everything I can to make her feel cherished without acting like a stalker. Mainly little things, but she recognizes them. Tonight I will bring flowers home because she is having a tough time. The last couple of times that I did this she kiddingly called me a "jerk" and said she doesn't deserve flowers. She realizes she has caised me pain but I try to show that I don't hold it against her. Again, leading by example.
Love them today even if they won't be here tomorrow.