How is polygamy behind the wifes back halal?

Asalaam everyone I have some questions regarding polygamy in islam and would appreciate some knowledge on this topic. Please read properly.

I understand that it is halal to marry more that one woman in islam but what i dont understand is how it is permissable for a man to do so behind his first wifes back as everywhere it states the man doesnt need the wifes permission.

How is this honest and just? Wouldnt this be dishonest as you would constantly be lying to your wife? Wouldnt that become unjust as youre hiding something very big that could impact their mental health once they do find out as the truth will always come out and you could prevented harming someones mental state by being honest from the start.

And then theres lowering the gaze as it states how are you marrying a second wife but lowering your gaze, surely your gaze must be up for you to decide to marry another woman? Unless its to help a widowed woman in need.

And then what about when youre being intimate with both of them? Youre hiding that youre having an intimate connection with someone else how is the woman supposed to be okay with this especially if its done behind her back.

In quran we are mentioned in twos threes and fours why are women described like this.

How is lying about your whereabouts halal in scenarios where one wife is giving birth and the other wife needs help will you continue to lie during this how will you be present for both how can you keep up with such deceit?