What R1 is getting at is there is no percentage and to even hazard a guess would be silly.
Both parties enter a marriage contract with the best of intentions. If both parties do not fully grasp what they are up against with constant deployments, absences, stress, money, temptations, and a thousand other complicated parts of military life, it soon becomes apparent if they are equipped to handle it or not.
Some couples do great. The spouse left behind is typically able to be independent and have a life that doesn't revolve around their deployed spouse.
Some do not fare well. They are ill equipped to handle it.
Your spouse will be put through an incredible test when you are gone. If they are the type that kisses you goodbye and gets on with things, they will be just fine.
My wife had a harder time adjusting at first, but she found friends and hobbies outside the military that have kept her sane for multiple and frequent absences, some short and some long.