I've stayed monogamous through two out of three marriages. (31 out of 33 years of wedlock.)
The first wife, 'the Incubator' insisted on 'sharing' with her sister. I found it distracting. She only lasted a couple years before she left me with the babies so she could go party. Swore I'd never make that mistake again. Three years of psychotic DisneyLand.
Monogamy's better, I highly recommend it. Its put my mind in a good place. It works for me. Not so well for wife two...there went eight years of my life. Even gave up meat for that bitch. I got better.
I'm sure this wife is my soulmate. We have honesty and cherish each other. We're still newlyweds after this long.
I hope you all find that. It's worth the path of Hell.