You cannot mix them. You are either under grace or under law. You are either working for blessing or already blessed in Christ. You are either enjoying your acceptance with God or you are striving to achieve it. There is no middle ground, no compromise, no in-between.
Marriage is meant to be a permanent bond, a lasting relationship.
To leave a marriage and enter another union is adultery and unfaithfulness. However, if one partner dies, the living partner is freed to marry another and has no guilt or obligation. Now Paul takes that reality and applies it further. Just as we died to sin, i.e. we were separated from the dominion of sin through Christ, so now we are told that we have died to the Law as well. We have been separated from the realm of Law, delivered from its dominion, liberated from its rule through our death with Christ.