Three-year relationship bedroom help

My gf (32) and I (26) have been together for almost three years. But I feel we are on opposites on sex. I feel im not getting her cues for some reason and its frustrating her. We can be watching tv and she'd ask me what do I wanna do? And I usually shrug my shoulds and day maybe cuddle, posably a bath idk Im chilling. But then she'll get up right away and leave the room. I always ask what's wrong and she just sulks. Eventually she will tell me how she shouldn't have to say "she wants sex" everytime she wants it. How we only seem to have it when I want it. But I didn't realize she was wanting to have sex and I didn't know if I wanted to or not. I know it doesn't make sense, but if kissing and cuddling doesn't happen first, I need verbal cues to see if I'm in the mood or not. I know we haven't had sex where we both orgasm, we have had sex many times where I only get off and I've mentioned I hate the imbalance but I just don't know how to fix it. It feels when I try to joke about going down on her or flirt about wanting to do it. She'll shrug her shoulders and mention "yah right, you barely do." Or it feel like she'll turn away from me in bed before I can get her off after my orgasm. I don't know how to fix this or if I'm missing something. I don't want to loose her and she's starting to joke about getting a hall pass or having an open relationship and I just feel like I'm loosing her and I don't want to loose her. I love her too much and I wanna fix this, any help is appreciated we are both in our first long-term lesbian relationship and it's all scary man.