There are no guarantees in life or love, just options and chances. Chances are here that if you don't, you'll lose him anyway so give him what he seeks here and pray for the best but be prepared in case the worst happens. These love vacations usually happen when there is a problem in the relationship and one needs time to think things thru before continuing. Now all space times end badly but this is one chance you'll have to take and see what happens but if he doesn't come back then chances were this relationship was never meant to be and failed the test of time. Good luck
