hypothetically
lets say if the husband is only earning rm2k, wife is rm10k on average, their lifestyle must be affected

or else,
if the husband earns 10k, and wife earns 30k
the range doesnt affect much

Good answer

When I was a doctor in the service (in Singapore) and still taking specialist exams, waifu made heaps more as she was an accountant with one of the big four companies (also in Singapore - we both pendatang'ed across the Causeway almost as soon as we graduated). She continued to climb up the corporate ladder while I continued to slave away in the public sector until I cleared all my exams (that took nearly 10 years, from 1st paper until all exit papers were completed). She took care of the bulk of the expenses.

Of course, things are different now, she took early retirement last year and I'm the one left holding the fort - so in our case, it was fair: early days, I took shelter under her umbrage (the original meaning, not the new mistranslation), while she's now enjoying the fruits of her labour in the form of a grateful husband who became a success in the latter years in no small part due to her hard work in taking care of the finances and freeing his time and mind and energy to pursue his studies.

So, even if it's $500,000 or even a million per month difference, I say stick with it - because we did it, and we're more successful together as a couple than we could have been apart and alone.