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The airlines will not care; they might call out your name a few times - but they will consider you a no-show.
As far as immigration is concerned, as long as you have a valid visa for the US, they also do not care.
So, the answer to your question is:
The only thing that raises eyebrows is if you pay cash for a one-way ticket at the last minute. So, try to pay for your final trip online with a credit card or book it through an agent.