Don't let the children put a wedge between you and your spouse. Don't let the children come between you. Remember little children do have big ears. Don't expect and fantasize about the fairy tale relationship. You know, the one where everyone instantly loves everyone else and lives happily ever after.
Frustrations stem from expectations.
The less you expect the less frustration you will experience. Not everyone is an authority on your relationship, although many will say they are. Do go with what you believe, not what others might tell you or what you dream about. And Don't expect it to be instantly all roses. Do let the biological parent discipline.