If the OP's wife wants to go faster .... then we can assume that at her comfortable max revs in top gear, she is not going as fast as she wants. He does not mention his own pace.
My question would be, is she spinning as fast as she comfortably can, but she Could spin faster, but nor with pleasure? if that is the case she probably has power to turn a higher ratio. If she is spinning as fast as her power allows .... then changing cogs or rings wouldn't matter.
I think most of assume (possibly incorrectly, but I did say "assume") is that 40x11 is simply too low a gear combo to get the speed his wife wants, comfortably and consistently, on the terrain they normally ride (mostly flat.) The fact that she might only be spinning 80 rpm isn't the issue .... if that is where she is comfortable.
I have a 48-38-28 triple with a 14x34 (it think 34) 7-cog cassette on my old Cannondale tourer. I often find myself wishing for the extra couple teeth I am missing compared to my other bikes, most of which are 50-34 with 1- or 11-28 or -32. Sure I could definitely just spin faster in 48x14 .... but it is not a pleasant experience for me. I have a certain natural cadence where I feel most comfortable.
So I would assume that the OP's wife, if she Could spin the 40x11 faster, could also be happy with a 44 or 46 ring.
The goal here is a happy rider. She isn't racing for cash or anything. She just wants to enjoy her ride, and finds her bike to be undergeared .... as far as I can tell.