A relationship is a system that functions within a state (the home). Peace time in the home should be the norm, pax necessitudo.
A question of how long peace usually exists in the home (the state) is a question about the quality of system, the relationship.
If the thread title implies peace is not the norm in the home, then the system (the relationship) is weak and the state, the home, is unstable.
Instability has consequences of frequent arguing, cheating and in severe cases divorce, and child support. In a severe case the state, the home, is subjected to outside legal intervention and liquidated, something common when dividing assets to settle a divorce. The state relies on the system.
Actively tending to the needs of the relationship by cultivating a system that disallows instability is the key to pax necessitudo, or in terms analogous to Immanuel Kant, perpetual peace.