Samuel is not exactly a story that is going to be useful. Eli was a horrible priest. So let's divert away and use Judah and Tamar.
Judah was supposed to give Tamar to another husband of one of his sons...
And if not he was supposed to marry her himself to keep the lineage going for his dead son.
But he didn't want to marry her either even though he was personally responsible for her being married to someone. And the moment she came up pregnant he was more than ready to execute her for being a prostitute....
But then she proved it was actually his child that she got out of him by being deceitful. "She is more righteous than I" was what Judah said. Judah was willing to waste his seed on a prostitute but unwilling to give her a child. (He had issues)
A young wife? What's not to like? Something was definitely wrong with these people.
A brother was supposed to marry a deceased brother's wife to continue his lineage for him. Also to provide economic support (life insurance policy) to her if he died. Others simply because of wealth married a second or third woman because they could...and Legacy was a huge prize of pride in the Ancient Near East. The more children and the more wealth they generated the larger the legacy.
One day you and I both will leave Earth bound for Heaven. What legacy will we leave behind? One of substance or one of sin and self service? There are many notable people in history that have left us legacies of their actions. Edison, Einstein, Benjamin Franklin, George Washington, and even Henry the 8th.
Polygamist want a legacy through one or more of their children. Through Jacob we have the Nation Israel. (Big legacy)
As far as hardships?
Every life has hardships...even the wealthy elite have hardships. Life is not easy for anyone, anywhere, at anytime throughout history.
Im just asking is it really loving to have sex with one wife, and have sex with the other. That is the overall question. Does God approve of this? or did God make a template in the Garden, one man and one wife. That is all I am looking to be found in being answered @JohnDB. Man can say a lot with words.