I'm not sure how much applies, because you're focused on quality, and I was focused on frequency. Also, a woman's perspective is likely different.

First, I communicated how depressed I was about the situation. She got defensive, but I told her she didn't have to be, because she didn't do anything wrong. I was just sad. I reassured her that I would never break up with her over this. She cares about me so she wanted to improve. I communicated about this about once every 1-2 months at the beginning to avoid pressuring her. All of this reduced pressure on her. At the beginning, I focused more on myself and less on her. It was much harder to do things for her when I felt like it wasn't reciprocated. I also was able to enjoy my own hobbies/friends/goals.

Second, was focusing on improvement. I started working out (for myself). We worked more on nonsexual physical intimacy (physical affection, massages, back rubs, cuddling etc). We also watched some sex positive shows like sex education on netflix.

Third, was focusing on build up. I made it clear to her that just because she teases me or does something sexual, doesn't mean we had to go all the way. So, she could tease me throughout the day again without worrying it had to lead to more (something she enjoys). The same went for me. Just because I touch her in a certain way doesn't mean we have to do anything. I also texted and flirted with her throughout the day to get her riled up.

Fourth, I tried to work on sex quality. I used an app to track her cycle and gauge when she would best be in the mood. I learned tips/anatomy on reddit and in videos. We tried new things. I slowly accustomed her to accepting oral. I realized if I could get her in the mood one day, I could build it into a streak. It's much easier to keep her in the mood than to get her into it. At this stage, whenever she did something sexual I would put in the effort to show her how happy I was and how much I appreciated it.

Fifth was going on vacation. We went on a trip, so neither of us had anything else to worry about. We saw sites and got good local food during the day. At night we had fun. We also had a giant comfortable bed that gave us good night sleeps. Good sleep is critical for good sex imo.