Guy dilema: Advice please?

Well there is always that daunting option of pulling him aside and confronting him on the whole situation.....Yes it would be nerve-racking but at least he would know where you stand, and at least you would know that you tried. If he decides to get his heart torn to pieces, and dumped like yesterday's trash by that other chick then that is his agency to choose so, and then comes that cliched phrase of there being plenty of other fish in the sea (and much better ones at that). :)