Can we file married but separate IF WE LIVE IN THE SAME HOUSE

[Marketstar]

Yes, you are not required to live apart to file Married Filing Separate.

However, Married Filing Joint generally yields a better tax result than Married Filing Separate even if one spouse earns little or no taxable income

Generally, filing jointly will give you a bigger refund or less taxes due. When you file separately, your tax rate is higher and you won't be able to claim a number of deductions and credits:

See Is it better for a married couple to file jointly or separately?