The bottom line is that you can't run someone else's relationships. They are what they are & what will happen will happen. First off, recipes don't always turn out like we think they will, & if they do, there is probably NOTHING you could say to change his thinking in the first place.

All you can really do is be there & be supportive if it does happen. Honestly, the hurts that we encounter in our growing up relationships are learning experiences & they aren't anything that will destroy us....but are what we build on to make future relationships better.

If you try to control his life at this point....you will probably only drive him away....if you end up consoling him if something does happen, it might only bring you more together (if that's what you might be hoping?)