However, if you pay to get the Trek to fit you, it won't necessarily fit anyone else. Even if you and the missus are the same height, women's proportions are rather different
I reckon you may just need more time in the saddle if new to cycling.
Feet - are you riding clipless? If so, look at cleat position, plenty of online guides if have the patience. If flat pedals, look at shoes, you'll want flat, stiff soles, make sure shoes not too tight and socks not too thick
Ref the fit, call the Giant store in Liverpool, I am told the Guildford store charges £60
http://www.giant-liverpool.co.uk/
Or Google bought this place up in Warrington, £100 for a fit
http://www.cyclehouse.co.uk/info/bike_fit.php