Why haven't I received my return after 5 months since the IRS accepted it?

My return was accepted by the IRS on 11 Feb, and it is now mid-May. For the last 15 years I've always received my return within a month of filing. What's weird is that I received my state return after just 3 weeks but no sign of my wife's return or our federal return. The IRS site just tells me it's still being processed. Calling the IRS help line just tells me an automated message that... It's still being processed. This is deeply frustrating. Does anyone know if there's anything I can do to follow up on this?