In case the fact has somehow escaped you, United and Lufthansa are about as close as two airlines can be without actually getting hitched (and they probably would if only they could get Uncle Sam's blessing). They make no secret of their true affections, and to flaunt their deep commitment and spread the love around a bit, as it were, they're doing their very best to entice you to come to the city where they first met— Frankfurt, Germany.
Hardly the City of Love by any stretch of the imagination, it's really more the kind of place where money talks and at these prices you should definitely listen up, because some of these fares are good enough to have you seeing stars too, or at least dollar signs.
Currently starting at $420 with taxes from New York for November travel and $470 from Boston for September departures, they are available on non-stop United/Lufthansa code-share flights from many of Lufthansa's U.S. gateways, and most likely from a host of other airports with connections on United. From some cities we have only found the best fares on a couple of days, while from others they are more plentiful.
As with any any relationship, this one has its ups and downs, and these fares do seem to fluctuate daily, so if you're not ready to make a commitment just yet, you should at least keep your eyes open.