Problem: How do you know if your wife is ready for plural marriage?
Answer: She's not.
Solution: Don't do it.
But, how do you know if your wife is ready? Well, not if she says she is, as strange as that sounds. The pattern that I've noticed, is that for most women they take a while to come around. Once they've grasped the biblical knowledge of PM, they then need to grasp the idea of it happening in their home, and that's a whole other thing to deal with. This could take years of back and forth. Sometimes they want another wife in the house, and other times they want to make sure their hubby would never ever bring someone else in.
Preparing for PM is like preparing for a baby. So, you want to have a baby. You read all the books, you set up a room for the baby, you prepare as much as you can. You buy all the baby things you think you need and you listen to all the advice you can (and try to figure out what is right because it's often contradictory). Then you get pregnant, and the pregnancy is much harder than you thought it would be. The morning sickness doesn't seem to stop like the books said it would at 12 weeks, and they don't talk about all the pain you have just from baby turning around inside you. Labour kicks in and it's nothing like anyone described. Then you have a baby. A tiny little newborn baby that you don't know what to do with! All those books don't help. All that advice doesn't help. All the latest gadgets you bought don't help. Nothing could actually prepare you for what it was going to be like to have a newborn, just how hard it was, how much you had to rely on God and your husband to get you through it, how you realised that you truly knew nothing. Because your baby never read the books. Your baby is an individual with their own needs. You find that you aren't the mother you thought you would be, you lose your cool sometimes, and sleep deprivation is far more toxic than you ever realised.
And so it is with plural marriage. You might spend all the time preparing, and you think you know what it will be like, and you think that you have read all the books and got all the advice and you'll be able to do it better than others. But then another woman came along and she's nothing like what you had planned. She's her own individual person and she didn't read the books you did. You find you aren't as calm as you thought you'd be, and sometimes you lose it. You find that there are some really deep down insecurities that you had no idea existed that have now come up to say hello, and you don't know what to do with them. This was a hundred times harder than you ever imagined.
You see, to know if your wife is ready for plural marriage, is not to know if she is ready to have another woman in the house, or whether she's ready to share you. It's definitely not knowing that she's understood it's OK biblically. It's knowing that she's in a place where she's ready and able to go through the fire and come out the other side without being destroyed.
Read that again. It is not about her being accepting of plural marriage, it's about her being willing and able to go through great hardship and difficulty and survive it.
If there is any doubt that she is ready, that she could handle it, then don't do it.
There are too many failures. Too many people rushing something that takes much longer than you think. Too many people not knowing how difficult it really is, and that that difficulty is normal and will take you to an amazing place, if you have the strength, courage, and ability to ride it out.
One other thing they don't tell you in baby books. No one, no words written or spoken, no images, can ever describe to you the love you will feel when you look at your newborn baby in your arms. You can't possibly know until you experience it. I understand it's the same with plural marriage, there is much joy and love to be experienced, something that can't be understood until you're there in it.