I agree...
Join in or enjoy the view.
However, this does blur the line of "consenting" adults. Talk to her first and make sure that she OK with it...
Also, it seems to me that she has some repressed sexual desires that she may be too shy to share with others. If you take it slow, you may be able to encourage her to share with you. Maybe share some of your secret fantasies with her first...
Will she let you use the toys on her? Maybe she's too embarrassed to do it herself...
Have the two of you ever tried masturbating in the same room?
Gently push those boundaries so that you can get more comfortable with one another.
It seems that you have only seen the tip of the iceberg as to where your sex life 'could' go...