Does anyone know of why it asks of spousal info? I am not filing with my spouse.

[xmasbaby0]

Are you filing married filing separately?

If I am filing a separate return why do I have to list my spouse’s information on my return?

Even if you file separate returns (the worst way to file) you each have to list each other's SSN's and some other information on your own tax return.  The IRS can then cross check to make sure you are not "double dipping" for itemized deductions, dependents, etc.

If you are in a community property state, there is more information that will be needed.

Community property states:  AZ, CA, ID, LA, NV, NM, TX, WA, WI

https://ttlc.intuit.com/questions/1901162-married-filing-separately-in-community-property-states

[SplintEastwood]

It probably has to do with any possible dependents.  Dependents can be claimed on only 1 return so they are verifying that your spouse is not claiming the same dependents.