Some background you might skip:
My new girlfriend is a pretty interesting chick. She's young, doesn't feel she's a special and entitled snowflake, and takes life quite seriously, she's poor and managed to study Medicine, she's now a resident doctor. That looked like a bonus to me, she's low maintenance, she doesn't demand a lot of attention.
The downside to it is, she's busy as fuck and tired as fuck. Other stuff worth mentioning is, despite not being a CC rider she's not sexually conservative. She requires frame control. She also said "no women wants to date a guy beneath her" for all that matters.
Now, she requires frame control and it so seems I lost mine by "empowering" her too much and telling her she holds too much value for me. The irony being, I might tell her she's a lot more valuable to me than she really is.

Anyway, as for what happened:
I always put effort in making sex damn great for her. I often do oral, sometimes I'll stop PiV to go back to it. From two weeks ago to now, she stopped bothering reciprocating it. In two weeks I didn't orgasm during sex on two occasions, because she got overly sensitive after she came and passed out soon afterwards.
I can understand how tired she is working sometimes over 100 hours a week but that doesn't make me want to accept the lackluster sex. And it's not hard to make me cum either way.

Now, I would approach the subject and label it "need for proper communication", but she made a comment that was a cold shower in the whole relationship: "You must be really upset about the weekend".
I waited for a moment to think and she said "you're in silence because you agree". After some time I said "not exactly", she challenged me and I said "I am upset but that's not enough to make me label the weekend as a loss of time".

Anyway, the whole thing tipped the relationship's balance to the wrong side. If I'm staying on it now it is because I'm expecting her to make up for it, which although isn't literally ignoring Briffault's Law as we write it, it is still somehow being naive.

Ranting and venting aside, the question is:

How often and how likely is it for a woman (for those who skipped this far, new girlfriend) to SPONTANEOUSLY up her game and offer better quality sex in a relationship provided that her partner (me) isn't willing to change anything about how he acts (not worth the hassle) but has informed her (by agreeing to a statement made by her) that sex is lackluster?

Edit:

I'm yet to meet a chick that's worth half of the hassle that's keeping a relationship the fail safe way and I doubt any woman is worth it by herself. I'm not looking for children as of now, nor for someone to share living expenses. Basically, either I'll commit to a girl that makes herself less of a hassle by keeping her nature in check, or I will not commit at all. Spending time with this chick was more pleasant than spending it with new chicks, on average, so I gave her commitment when she asked for it. She had a shot.