Most lenders limit people to a set percentage, staring at around 35% and going up to about 50% for high earners, as obviously the remaining 50% will be more than enough to live on. Varies from lender to lender. Many lenders assume interest rate increases before working out this percentage.
My opinion would be that you should remain well below such limits.
When we were looking for a mortgage I reckoned based on interest rates 2% more than we could get , we should have one of about 1/3rd of the higher salary. So if one of us lost a job it wouldn;t be a huge issue. Though mine and DH's salaries are of a similar level.