This probably isn't the answer that you want to hear, but it's a bad idea to date someone with the intention of "molding" them to fit what you find attractive. The reason that your ex stopped bodybuilding after she starting dating you was probably because she never had an interest in bodybuilding to begin with, and was forced into that lifestyle by her then-husband. Her leaving the sport probably had nothing to do with your "kindness and lack of pressure" toward her.
I dated someone who was into powerlifting, but she was always interested in weight training, and when she met me, she wanted to train heavy with me without my even suggesting the idea to her. If she is interested in bodybuilding, or for that matter any kind of hobby or activity, encourage her, but don't force her into a training routine rooted toward your personal desires. Or, get into bodybuilding yourself, and if she is getting involved after seeing you dive into it, go from there.