Insecurity. Be more sensitive to this and touch non-jiggly parts, like shoulders (especially where they meet the neck--that may be just me but I love that) and dish out verbal compliments on other parts to build her confidence for touching later. "Your legs look really good in those shorts." Let her catch you checking out her rear-end in an approving way. Come up behind her and run your finger down her spine and stop just above her bum. If you come up behind her to give her hug, try to embrace in the skinniest part--just below the breast. If she's sitting with her feet up, run your finger down the curve of her foot, unless she's really ticklish.

Marriage is the triumph of imagination over intelligence. Second marriage is the triumph of hope over experience.
(Oscar Wilde)