Need advice?

I've been very interested in the realm of BDSM for the last couple of years, however I have never experienced it firsthand (only vanilla type things like blindfold, held against will, etc.) I have been in a relationship for the past four and a half years to a man I love very much but I don't think he's interested in taking that part of our relationship to the next level. I don't want to cheat on him, I would never do that but when I mention things I would like to try, he seems to shy away from it or tells me he'll consider it and never actually does anything. And this is something I truly would like to experience. Can I get some advice on what to do?