There are several synonyms for the phrase "say I do" that one can use when talking about wedding vows. These include "exchange vows," "make a commitment," "affirm your love," "pledge yourself," and "take the plunge." Each of these phrases highlights the profound and life-changing nature of marriage, as they all refer to the mutual promise shared between two people to love and support each other until death do them part. Whether you choose to say "I do" or opt for one of these alternative phrases, the sentiment behind each remains the same: a deep and heartfelt commitment to your partner.