@jfiler20
“Easier“ does not mean legal. And tax laws don’t have to make sense, just look at anything Congress does on a random day. However, I double checked IRS publication 501 and there is a statement that pertains to non-resident alien spouses. You can qualify as head of household if your spouse was a non-resident alien for the entire year, and there is no mention of a rule that you must be maritally separated.
(However, for resident aliens and US citizens there is a clear requirement that the spouses must live separately for the entire second half of the tax year. If they co-habit, even briefly, then head of household is not allowed.)
