If my wife and I were only together The last two .months of the year can we file married septate

If you are legally married then your filing choices are Married Filing Jointly or Married Filing Separately.  Form a tax standpoint it is best to file as Married Filing Jointly even if one spouse has little or no income.

You can always file Separate or Joint even if you don't live together or if you live together.  

Why do you want to file Separately?  Joint is almost always better.  

Here's some things to consider about filing separately……

In the first place you each have to file a separate return, so that's two returns. And if you are using the Online version that means using 2 accounts and paying the fees twice.

Many people think they come out better when filing Married Filing Separate but they are probably doing it wrong. If one person itemizes deductions then the other one must itemize too, even if it's less than the standard deduction, even if it is ZERO!

And there are several credits you can't take when filing separately, like the

EITC Earned Income Tax Credit

Child Care Credit

Educational Deductions and Credits

And contributions to IRA and ROTH IRA are limited when you file MFS.

Also if you file Married Filing Separately up to 85`% of your Social Security becomes taxable right away even with zero other income.

See …….
https://ttlc.intuit.com/community/married/help/is-it-better-for-a-married-couple-to-file-jointly-or-separately/00/25590

If you are legally married on December 31 of the year, then you file your return as if you were married for the whole year.  You can file jointly as long as you both agree, even if you were separated part of the year.  Jointly filing almost always results in lower taxes, but it depends on your circumstances so the only way to know 100% for sure is to make test returns both ways.