You are not taking into consideration what Paul has already stated:
1 Corinthians 7:39
King James Version (KJV)
39 The wife is bound by the law as long as her husband liveth; but if her husband be dead, she is at liberty to be married to whom she will; only in the Lord.
This speaks of normal circumstances, this...
1 Corinthians 7:15
King James Version (KJV)
15 But if the unbelieving depart, let him depart. A brother or a sister is not under bondage in such cases: but God hath called us to peace.
He has made it clear a brother (husband) or sister (wife) is not bound in such a case as having an unbelieving spouse who wishes to leave the marriage.
We create much confusion in Paul's teaching by ignoring what he has said:
1 Corinthians 7
King James Version (KJV)
2 Nevertheless, to avoid fornication, let every man have his own wife, and let every woman have her own husband.
8 I say therefore to the unmarried and widows, it is good for them if they abide even as I.
9 But if they cannot contain, let them marry: for it is better to marry than to burn.
If a woman, through no fault of her own, has a husband who is not a believer who wishes to leave the marriage, and, we ignore what Paul has said in such a case, then the believing spouse who let's the unbelieving spouse leaves is then left to the likelihood of sin against God.
In such a case, they are not bound. They are not under bondage.
God bless.