Why is my Texas income causing my taxes owed in Maryland to go up?

I live and work here in Texas. My wife lives here in Texas also but her office is in Maryland. She only reports to the office once a quarter for 3 days so 12 days a year total. Turbo tax is suggesting that we owe a lot of money to Maryland. When I completed the state tax portion, I only reported her income earned in Maryland for the Maryland taxes. When I remove all of the income earned in Texas from our federal return, it is lowering the Maryland state taxes owed. Why is our Texas income affecting our Maryland tax return when I did not include any of the Texas income on the state return and only put the Texas income on the Federal return?