It takes two people agreeing with God to form a true marriage. If marriage was only TWO, then your spouse's will cancels your will. Marriage would then become very unstable because at any time when ONE of the TWO has a moment of weakness the marriage could be ended. Contracts are based on you performing, but ONLY IF the other person performs. A blood covenant in the bible was the most serious of all covenants and could not be annulled.
Marriage is a blood covenant.
The biggest weapons of your warfare are prayer and fasting.