Keep telling your wife how you feel, and that you think that she is beautiful. Encourage her to by some new clothes...some that are flattering to her figure...and keep complimenting her...every day...keep reminding her how much you love her just the way she is.
Nordstrom's and some other major stores, and some make-up stores will do makeovers, plus a new hair style might help her feel better. You usually have to pay for the make-up makeover, but a spa day might be just what she needs...get her a gift certificate and lovingly give it to her, letting her know that you love her just the way she is, but that you understand how she wants to have a different look. Nordstrom's and some other stores also have clothing consultants to help find just the right look for her. My sister gave me a make-over for my 30th birthday...it was a lot of fun. I got a new hair cut, a new make-up look, and a new outfit...just what I needed...I was depressed about my looks, and that was just the pick-me-up I needed. Be tactful about the way you present this idea to her, so she doesn't take it the wrong way...in the middle of an arguement is not the best time to suggest it.
I am now a size 18...almost down to a 16...and I am happy with myself just the way I am...but I would like to lose more weight for the sake of my health. My tummy sags after three kids...the price a mom pays for wonderful kids. I wear tummy support underwear, and that helps me look better in my clothes. I wear a lot of jeans and t-shirts, but when I go out somewhere, I try to look a little more feminine.
Join a gym together, or if that is not feasible financially or timewise, try to work in a walk together several days a week.
Bickering is part of marriage...try not to argue back on the issue of her looks...it's a losing battle...the wife is always right...LOL. When you are not arguing, tell her how much you love her...buy her some sexy lingere...be sure you know her size...check her clothing tags when she's not looking...gift-wrap it...take her out to dinner...be frisky with her...be romantic...make it all about her.
I think I am repeating myself here...hang in there...my husband has done these things for me, and that has helped my own perception of my body...I'm not the skinny young thing my husband married 26 years ago, and that's OK...just don't tell your wife that she's not the same skinny person she used to be...she'll take it the wrong way...LOL
Compliments, compliments, compliments...especially when she has gone to the trouble to look nice, and even in the jeans and t-shirts...Becky