Hubby and I almost didn't make it when I lost the weight. At first, I was like you, you know? I didn't understand what the problem was - here I was, forty pounds lighter and getting hit on by guys at the gym, but my husband is acting like a total knob. It made no sense, but I have since read how common this is.
It's a change, right, and you're at the gym more, with her less... also your attitude will have changed; you're more confident now, more masculine, and this can make your partner nervous. She will likely get over it but it may be a bit of a bumpy ride at first. Very, very common when one partner improves dramatically, no matter what it is - education, fitness, career...
Hubby used to try to sabotage my diet when I first started this. I'd be eating protein and fat, and I'd come home from the gym to pasta on the stove and French bread in the oven. Now, I'm the kind of person who just turns it off when I'm dieting, but I felt disrespected.
He loves the "new" me now, but it took a while.