Hi Sarah. Welcome and, by the way, sorry you're here. I'm sure others will chime in, but if you've read some of the other posts here, you'll see you're not alone. Some places to start: Have you bought the SSM book yet? Have you shared it with him? You said you ruled out physical problems. I'm assuming you did a testosterone check. Is he on anti-depressants? Most of them are libido killers. Is there a body image problem? Have you or he gained a lot of weight? Is he having an affair? Is he gay? Is he willing to try to save your marriage? Are there kids involved? Did you used to have a good sex life? When did it change?
Answering some of those questions will get you started, and help others help you.
Just to get you ready: it's a long road, and it doesn't always go happy places.
