How come men can be sealed to multiple women but women cant be sealed to multiple men?
It’s not that simple actually. If a man is living and his wife dies, then yes he can be sealed to another living woman. If a woman’s husband dies, she cannot be sealed to another man. This harkens back to polygamy. God has not seen fit to explain to us why this is so, or why it is allowed during some generations and not others. So I can’t give you anything more than man’s best guess on that, all of which I think are insufficient.
Women can be sealed to more than one man after they are dead. For example, I know a woman who had been married twice, but never sealed. Her first marriage ended with her husbands death. In her later years, after her second husband had also passed, she was reactivated in the church. She went to the temple and chose to be sealed to her second husband. One of her children chose not to be sealed to her at that time, because he wanted to be sealed to both of his biological parents. He waited until she had passed. Then he had her sealed to her first husband, and himself sealed to them.
How will this all work out in the eternities we don’t know for sure right now. One temple president said that it doesn’t matter specifically who you are sealed to, what matters most is that you are sealed.
I hope that is helpful.