The 5 Love Languages
Excellent book on why couples might not feel loved in a marriage. It discusses five “love languages,” or methods of expressing love. Knowing them is valuable, but the larger point is that Person A might not experience love the same way as Person B. Person A might like “Words of Affirmation” and “Physical Touch” and simply assume that Person B is the same. When Person B isn’t, they feel unloved, which starts a cycle.
A seminal book on marriage. Should be required reading post-engagement.