If you do not have any dependents (since you say no kids, this would mean perhaps a dependent parent), then you do not qualify as "head of household."

See this page from the IRS Publication 501:

Married persons living apart. If you live apart from your spouse and meet certain tests, you may be considered unmarried. If this applies to you, you can file as head of household even though you are not divorced or legally separated. If you qualify to file as head of household instead of as married filing separately, your standard deduction will be higher. Also, your tax may be lower, and you may be able to claim the earned income credit. See Head of Household, later.
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You may be able to file as head of household if you meet all the following requirements.

1. You are unmarried or “considered unmarried” on the last day of the year.
2. You paid more than half the cost of keeping up a home for the year.
3. A “qualifying person” lived with you in the home for more than half the year (except for temporary absences, such as school). However, if the “qualifying person” is your dependent parent, he or she does not have to live with you.