If your wife came to you (husband) and said I want to see a BBC fuck your ass, suggested you watch some gay porn and even bought a big black dildo, would that convince you to say yes?!!! Extreme example I know, but some people just aren’t into things. It’s already been mentioned a little, but move slowly. Begin to explore other sexual fantasies both of you talk about. Find local sex or kink clubs. Go, but discuss that there are no expectations to do anything. Just enjoy the sexual atmosphere. Nude beaches or lifestyle resorts. Pressure is a huge turnoff. As you both get more comfortable, these events will serve as discussion topics. She may not want to jump right into being fucked by an anonymous BBC, but maybe it starts w playing w just another guy (white guy, average guy, whatever). Alcohol can help in these situations, but in great moderation. Loosening inhibitions is the goal, but not getting so intoxicated you make a regretful decision. Also don’t put any pressure on her. That’s incredibly hard to do as a guy, but it’s an instant turnoff for her and will only set you back.