I think your girlfriend ( wife?) has spent so much of her life trying to please you ( and I am not saying this is all your fault) that she has no clue what she wants or likes.
You've known her a long time- what is your gf good at? what does she enjoy?
Your girlfriend needs to build some self esteem. Take every opportunity you can to praise and compliment her. Do not do this insincerely. It will get old for you and will not help her.
When your wife looks pretty tell her specifically what you like about her outfit, hair or makeup.
When she makes you dinner, thank her.
Ask about her job. Ask for her input regarding things you are contemplating.
If your gf has a hobby, encourage her pursuit of it. If (for example) she likes to paint- buy her art supplies as a no - occasion present. Ask her if she would like to enroll in an art class. Make it a point to hang her up some of her paintings in your home and or/ office.
In short, make it clear to your gf that she matters to you.
Talk is cheap. If you love her, show her.
Here is a great idea. Buy this book and YOU follow it in regards to your gf. I bet you get great results.
http://thelovedarebook.com/
I wish you and your gf all the best.