Hi,
Congratulations on your son! A very exciting and very exhausting time :) Yes, I also remember the first few months as almost one constant feed. My daughter used to dose off during feeds and also used to 'comfort suck' rather than feed, making feeds extra long. If your son's falling asleep your wife could gently wake him up by stroking his ear and also listen out for a swallowing sound and seeing if his jaw's moving up and down to check he's actually drinking. If not then moving him might do the trick to remind him he's supposed to be feeding!
If you find that he is comfort sucking, like the last lady said, a dummy is an option, although there may be a risk this early on that he'll get nipple confusion. Might be best to wait a few weeks longer. We resorted to this after a few months and it did comfort her very well and I got a better night's sleep. You might find that in the next few weeks his feeding will have calmed down anyway, so I would say if she can put up with it for a bit longer then carry on with the frequent feeding, sounds like she's doing a great job!