No idea how you've interpreted the lyrics. I.e., when talking about:

'She says we've got to hold on, to what we got. It doesn't make a difference if we make it or not'

I'm clueless to how you understood it, but "make it" comes from "make it in life", which means becoming successful in life. Due to the financial struggles in the story, the girl is saying their life together will be good even if they never become rich.

“We Got each other, and That's a lot for love”

Do you know who also 'has each other'? People who are trapped in a loveless marriage.

That's exactly his point. They actually have each other's back, which is what trapped-in-a-marriage couples don't. There is no need for quotes in "having each other" in the song's context.

'Oh, We're halfway there, livin' on a prayer'
As previously established, they are not even at the minimum

Exactly, which is why they are only livin' on a prayer. You describe what are actually the lyrics intentions every time you try to prove it crappy.

Now, to Paraphrase the next verse, he gives up on his own creative dreams and sells his six-string guitar, and his lady is now crying herself to sleep at night wishing she could run away from it all. But our hero assures her that one day it'll be alright.

He is not given a "hero" treatment. The lyrics are taken from...

a song for all those people struggling through hard times

...where he doesn't offer any flowery words, only a description of the cruel reality without any progress, where the couple every day can only try surviving until the next morning. This is the reality of so many people, perfectly described. There is nothing to make it seem good.

The song describes the life of people who were hopeful during youth, but got their hopes and dreams after get crushed over the years, without any forseeable chance of things getting better in the future, but not quite giving up yet.