If you’ve checked “Your Personal Info Summary,” and you show up on that page with your dependent but no spouse, with your filing status appearing as “Head of Household,” then things should be fine (and the program should let you file that way).
But let’s discuss the joint filing question you’re seeing. Where in TurboTax is this showing up, and exactly what does it say? (For example, is this something which comes up as an error when you do the review?)
@roahsafia, our ability to troubleshoot with the program is limited in this venue, but we may be able to explain what’s going on if we have more details...