Finances: Satan can work through money to cause strife, disappointment, and anger to rage within marriages. God gives us the power of love and self-control. We must not work out of fear, but be honest where we are financially, communicate well with our spouse, and get back to honoring God with how we steward what He gives us.
Sharing daily responsibilities: Whether it's as simple as doing laundry, loading the dishwasher, parenting, or anything else, God ultimately designed marriage between a man and woman for us to be helpmates. We are to compliment each other in what we do. We are to serve each other as Christ served. We are to share in the marriage responsibilities. Satan will use cracks and gaps to make one feel like the other isn't pulling their load. Be sure you are pulling your load. 100% from each side.
Faithfulness: As a man would leave his father and mother, and become one with his wife, we are expected to stay faithful to each other. This could be with another person, a hobby, work, or numerous amounts of other things that satan will use to cause you to loose focus on your spouse and ultimately desire someone or something more than them. We must fight for our marriages, fight for each other - not against each other. Your spouse is not the enemy, satan is. Satan would love to see something that God designed and ordained be destroyed. Do not give him that pleasure. Fight!