If she is timid, she has not said, "not in a million years". Occassionally, but not too often, slip it into conversations that you feel a bit jealous because you saw guys eyeing her body up. Tell her that it was obvious that they thought she was pretty, because they kept glancing back at her. This subtle stuff will help her to become more aware over time that other men want what you are having.
If you do it too often, she will pick up that you are "pushing her" - and she won't like it. The goal is to simply make her feel that she is still pretty even though she has been married for awhile and in better shape that she realises. Her mind will feed on this like a snowball even though she won't admit it.
Make sure she sees the evidence that you love her deeply, because she will be more inclined to listen to what you have to say about almost any subject.
She must notice her marriage is rock solid, and if she did get naughty by flirting (or something better) under the influence of alcohol, that you would be understanding of her inner hidden needs, and DIVORCE IS NEVER AN OPTION.
Many wives do want to have a fling or two, but the fear of the damage it might cause to their marriage, STOPS THEM doing it. True love has a forgiveness component.