No this isn't our first, and the great thing about my wife is that she's not like most women. I just remember when we had our first she had a hard time finding clothes that made her feel good, and she is not the one to, how would you say this..... "scrub it". Even though she is pregnant, and even after she had our first she always kept up with herself. And for some reason I don't see her getting too mad....
I never understood why women get upset over getting clothes from a plus sized store... Lots of people bought me new clothes after I had my son, and they were all plus sized. I'm not huge, mind you, but just big enough that I'm at the low end of the plus sized scale. Personally, I appreciated the new clothes, and was just happy they fit. Nothing is more embarassing to me than to get clothes that dont fit, then have to take them back to return them in exchange for something bigger. How mortifying.
I like to shop for a lot of my work clothes(which are all pretty casual) at Lane Bryant, but Torrid is good too. Torrid can get REALLY pricey though(like 75+ for a pair of jeans).
My suggestion, if you're even a little worried she will take offence to plus sized clothes bought by you, is find a sitter and take her up to Arundle Mills for the day and let her do the shopping while you carry the bags. Lots of "Yes Honeys" and handing out the credit card while you lug around her new found items will put you on easy street for a little while.
But when I go out, I still do my hair & makeup like I always have. 
C_Jo only purchases mediums for me, no matter what. 
