Need an advice for "thin"

my wife is too thin, but she cant eat much more! so what can I do to make her fatter?

why cant she eat?
and take her to a dotor if you think its bad
get her bmi (body mass index) correctly calculated so she can see if shes underweight or not for her age and height
she can take it from there
she might be stubborn about eating though, and probably has an image in her head of a beautiful person as described by the media
a lot of people in the media are not of average weight, and can be a little or a lot underweight
so if shes always comparing herself to these images and people then it will be hard to get her thinking the right way again

What do you mean she can't eat much more?

Is she refusing, or does she just get full quickly?

You got a good answer from jazlovestoskate concerning the possibility of ED, but there's also the possibility that she's just petite.

If she eats regularly and maintains a healthy diet, then she's still getting what she needs. Some people are naturally skinny and don't have huge appetites.

As long as she's not displaying any harmful behaviours regarding her eating patterns, you may just have to accept that she's small and love her as she is.

Get whole milk,use real butter in instead of margraine, get weight gain powder at gnc and make her milkshakes with it, ensure has a great shake called insure plus that has extra fat an calories to help gain and maintain a healthy weight,cook lots if mashed potatoes an rice and pasta with lots of butter and cream... Bake fatty sweets like brownies and pound cake...

Well, You have very limited choices. I would reccomend either getting her some protien powder and just mixing it with the foods she likes and do this everyday for as long as it takes. It will make her gain weight, but at the same time...build stronger bones and a better metabolism. I would also suggest that if she won't eat much, MAKE HER EAT. Depending on how thin she is will determine how much she needs to eat to gain a feasible amount of body weight/fat. If she refuses to do so, try taking a trip to her doctor or a counciler. A doctor would most likely suggest using a protein powder, or he might actually give you a prescription. A Counciler would basically explain to you that she would have no choice as to whether or not she eats; he/she would also go into detail [once again, depending upon how skinny she might be] such as the fact that she could suffer from anorexia. I hope all is well and wish you both the best of luck in life's journey. God be with you and your wife.
~Rachel