I'm not sure how you would expect too "see" those things. It's like saying you can see her thoughts and feelings. She could be a disaster in her head about it and you may never know. Maybe she tried to put extra effort into sex in the beginning when your relationship was newer, since you said she wasn't always like this. She might have tried to put her feelings aside because she was really into you and the relationship. But you say now you guys are in therapy and she uses it to talk shit about you, so maybe her issues with you are contributing to the way she is about sex now? I know if I upset with my bf or he's like talking to a wall I definitely am not into sex with him. I also was in a relationship two years too long and had zero interest in sex with him because he was terrible at it and I wasn't into him sexually because I wasn't in love with him. Whatever HER reason(s) may be you aren't going to get anywhere until you find out what they are. Maybe she's been trying to tell you and you aren't actually listening to her feelings, maybe she's not telling you at all, who knows. Not trying to put all the blame on you but Its hard for my brain to not at least consider that possibility. I spent a long time with someone who invalidated my feelings over and over and no matter what I said he only heard or saw that I was "complaining" about him without ever caring WHAT it was I was saying. He also always assumed he knew what I was thinking and why I said and did things even though he was often wrong but refused to believe me. I hope that's not the case with you two and I hope therapy helps you both. The fact that you are willing to go is huge and many guys would refuse so kudos to you for at least trying.