I'm not married yet, but through my fiance and seeing other SUCCESSFUL Christian relationships at work, I'd say their faith definitely impacts their marriage, not the other way around.
Faith is not the by-product or the end result of a successful relationship; marriage is not supposed to impact your faith. Faith serves as the unifier--a reminder in marriage about God's statutes and how He wants your marriage to work.
Particularly, if a person is married to a non-believer, faith can influence their spouse and help bring them to God. And faith also serves as a powerfule example to children of what a godly family looks like.