Since you have the original specs for the bike, now you need to determine what was changed, and if the parts installed are compatible with each other. How many gears are on the rear cassette? The bike came with an 8-speed cassette. Did a PO change the number of speeds in the rear? If he did, are the front and rear derailleurs compatible?

Derailleurs are designed to be used with cassettes of a specific capacity so you can compensate for the change in chain length as the gears are changed. It's possible that the wrong front derailleur was installed, or it was installed at the wrong height, and that will affect the gear change. When you get a new front derailleur, Shimano sticks a sticker on it to indicate the proper clearance between the largest chainring, and the bottom of the derailleur cage. Sometimes the Installer is instructed to kick-out the tail of the derailleur a little to enhance shifting and prevent rubbing on the cage. If the parts turn out to all be compatible, you may want to consider taking the bike to you LBS, and paying them to figure out the problem and solve it.

Or, if you like your wife's new bike that much, you could also consider trading in the "troublemaker" on a new Trek for yourself. I don't like to recommend solving a problem by trading, but sometimes that is the easiest, least aggravating solution. You didn't pay that much for it, and it's a relatively new bike, so you should do okay on a trade-in.