My DH and I will celebrate our 47th anniversary next Tuesday (8-31). We have two fine sons who have chosen us wonderful daughters-in-law and four grandchildren.
My DH had a stroke in 2001 and is now in early stages of Alzheimer's. Last week we began working with a therapist who specializes in Alzheimer's patients. During the testing, the therapist asked him to write one complete sentence about anything. He wrote "I love my wife."
My advice for a long marriage is to put your spouse first, even above yourself. Of course, this works only if both spouses adhere to this practice.