It may be okay to covet your neighbor's wife IF YOUR NEIGHBOR GIVES YOU PERMISSION FIRST. Otherwise, he might put a dagger through your heart, cut your testicles off, take fearful revenge, drop rocks on your head, or seek redress throught the Courts.
The Commandment, "thou shall not covet your neighbor's wife (no matter how sexy she is) is a general warning to get permission first - it was never meant to be a mantra to cross swords over.
Wife swopping may not be a sin if all parties agree, but it is definitely a contract that if any children are bred from swopping beds - all four need to share the responsibility of raising the unexpected children that result from the activity.
You can have 9 wives, as long as you can afford to look after them properly and keep them contented. At 18, a man may feel like having 9 wives to sex up, but by 41 even one wife may be too much for his disappearing libido. Having 9 mother-in-laws with abrasive tongues could cause some discomfort.
It is also written that a wife should not be away from her husband's side for more than two days. This means you should sexually cuddle your wife a minimum of 3-4 times a week, so her emotional happiness can be maintained. You will have a busy schedule if you commit to 9 wives.
So if you are unable to continue to provide your wife with the sexual expression that is promised on her wedding day, then you may have to become a cuckold and invite your wife to select some Bulls to visit her and make up the shortfall.
You should wash the Bulls' cars and weed their garden to thank them in a meaningful way.