Romans 7:3
So then if, while her husband liveth, she be married to another man, she shall be called an adulteress: but if her husband be dead, she is free from that law; so that she is no adulteress, though she be married to another man. So then if, while her husband liveth, she be married to another man, she shall be called an adulteress: but if her husband be dead, she is free from that law; so that she is no adulteress, though she be married to another man.
While her husband is alive, a wife remains bound by the marriage law to him, so that if she is married to another man she shall be called an adulteress. If her husband dies, she is released from that law, so that she is no adulteress though she is married to another man. The marriage illustration carries a spiritual meaning that believers become dead to the law through Christ's body so that they may belong to the risen Christ. In that new union they bear fruit to God and serve in newness of spirit rather than in the oldness of the letter.
The same bond holds a husband, so that seeking another wife while his wife is still living dishonors God and disregards the marriage bond. This applies even before the living wife has obtained a divorce, and to letting his affections center on another woman while his wife is still living. The living wife's obtaining a divorce does not make the husband's conduct right. Even after separation this remains true, for Caldwell had no moral right to marry Fannie although he had left his still-living wife three years earlier and she had recently obtained a divorce.