Paul like most writers of the time would not really understand what modern society is about, where religion is on the decline and we live in a multi-faith society,
Well, there were at least the Christian faith and the Jewish faith. And there were Jews who could be quite hostile to Paul and who tortured and tried to kill him. And I understand there were multi-gods, not only multi-faith. But Muslims had not gotten started, yet.
In ancient times a wife was more like the chattel of the husband and equality in relationships didn't exist.
Well, have you read how the men with David reacted when the Amalekites took their wives and children? 1 Samuel 30.
And Paul is clear how we need to relate with our wives >
"Husbands, love your wives, just as Christ also loved the church and gave Himself for her," (Ephesians 5:25)
"Husbands, love your wives and do not be bitter toward them." (Colossians 3:19)
I would say this is not how you treat chattel. But, of course, there have been the wrong ways people have used the Bible, and ones can use those people's bad examples to assume they represent what Paul believed and meant
In my opinion it was wrong for some members of her church to condemn a loving, faithful relationship on the basis of my lack of faith, when ther hadn't even met me.
Well, if she considers people in her church to be her Jesus family, I am at least curious how it is that you have not met them . . . after how much time? Paul, to me, makes it clear how we Jesus people are God's own children and each other's brothers and sisters. And here is how Paul says to relate >
"Let all bitterness, wrath, anger, clamor, and evil speaking be put away from you, with all malice. And be kind to one another, tenderhearted, forgiving one another, even as God in Christ forgave you." (Ephesians 4:31-32)
So, if this were how she shares as family with people in her church, Dave, I would think she would want to share these people with you. And if they are this good for her, I would think you would want her to get even more with them so she can be helped to do ever better with you.
But if she doesn't trust them, and therefore has kept things away from them . . . this is not how Paul says for us to share with one another as family. And I offer how Paul and Sylvanus and Timothy say they related with the Thessalonian Christians > "as a nursing mother cherishes her own children" > in 1 Thessalonians 2:7. By the way . . .
. . . from this, I can see how certain nursing Christian moms were role models for these men, of how to relate with God's children; so if they were examples for these apostolic men, I consider they were not considered to be chattel.
Now, of course, I don't know if her church has people who are an example of this; ones can know their Bible and tell people what's what, but without sharing and relating the way Paul says we are called to relate in love. But > in case she has not gotten with really Christian people - - if she does, I offer that they will advise her not to be unequally yoked with an unbeliever. But if she does not deeply trust and benefit from the ones she is with . . . I do not know how they really are, or how she really is; so I do not know why she has stayed with people she does not even trust, if this is the case.
I think there is more need, in your situation, than to just deal with the unequal yoke issue. And I think you could do well to get to know some people who are examples of how the Bible says to love; I mean people who might say they are first about pleasing God, and they are gentle and humble and kind and all-loving, but they do have Bible standards of right from wrong, but they are first about how we ourselves need correction > 1 Peter 4:17 with Hebrews 12:4-11. You might test someone who is dealing with you, by asking how that person has been getting personally corrected recently by God > I think a true Christian example would be glad to get into this with you
Paul, by the way, did talk about how he needed correction . . . as our example, I offer, so we also can benefit from how Jesus dealt with Paul > consider 2 Corinthians 12:7-15.