In general, I wouldn't bring a spouse into the work conversation. The most I might ever do is say something like, I haven't seen Larry in a while at work, has he been out or traveling? If she said no, he's been at work, I'd reply along the lines of, we must keep missing eachother, I really must track him down, putting it on me to find him. I wouldn't go into why or anything like that since it seems like overstepping the boundary.
I'd also leave him a voice mail and an email at work saying that I need the forms by X date or I will have to escalate the matter.