What would your W say about this arrangement? If she disagrees I don't think there is anything you could do anyway. If she agrees then there you go , your the parents, and an agreement between the both of you will work.
But I think this crying will pass as this becomes the normal, you have to expect a transition period.
Maybe keep notes on it, if a couple weeks later he is still upset, you there maybe a problem. Then with that past history of crying, you could talk to your W.
Me late 30's W mid 30's T 15, M 10 S4, S7 ILYBNILWY June 2015 In house S July 2015 W rings off Oct 2015 My ring off Feb 2015 Separate houses June 2016