I'm assuming she had RNY, just because it's the most common procedure.
Oh, and I wanted to say I think it's really great of you to look out for your wife like this
First of all, when you drink with a meal, the liquid pushes the food into the intestine much quicker, not allowing her to feel satisfied, or 'full' after eating. And that can lead to eating more than necessary.
Second, over time (a few months) what will happen is her stoma (connection from her pouch to her lower intestine) will stretch out. If her stoma stretches and enlarges, then she will be able to eat much more food at a meal than she should. The narrow stoma slows the food down as it enters the small intestine, so while eating you feel full and know when to stop.
Drinking with meals WILL defeat the effectiveness of the surgery to the point of her not losing as much weight, AND even re-gaining weight.
The 'norm' seems to be wait 30 minutes after drinking before you begin eating. And wait another 30 minutes after you stop eating until you start drinking again.
I personally wait at least an hour before I begin drinking again, because it just seems to take longer for food to exit my pouch than most. If I eat something 'solid' then I'm looking at a 2 hour wait. She'll get a better feel for what her pouch needs the farther along she goes ... basically, her pouch is in charge of her personal timeline when it comes to drinking, not always the clock.
I hope this helps, and feel free to ask anything you want ... this forum is packed with very caring people who know just about everything you could imagine! We're all learning as we go too!
Good luck to you and your wife, hope to hear from you again!