My impression is there are a lot of programming jobs where having a terrible work/life balance is expected. I'm a man and I would avoid such jobs. Perhaps women, including those who earn CS degrees, are statistically more likely than men to feel the way I do about work/life balance. The result would be fewer women working in the field without the environment being sexist or discriminatory.
How about "pulled away"? Maybe it isn't politically correct to desire being a stay-at-home mom, but it happens rather often. Sometimes this is an unexpected turn of events, with changing life priorities. Sometimes it is the goal right from the start.
I met a woman in college who literally said she was getting her MRS degree. That is, she went to college to meet a suitable husband and become a "Mrs.", as in "Mrs. Doe". It happens. This is real.
It's not a problem to be solved unless you have a negative attitude toward homemakers. People choose their own path in life. This might not meet your standard, but your standard might not maximize life satisfaction for everybody.
Was she taking computer science?
If we're going to talk anecdotes here, every computer science major I've ever met has done it either for the sunny career prospects or because they were genuinely interested in the subject matter - and usually both. I do not buy your premise that students are graduating from computer science in order to not have a career in it.
My wife: was capable in computer science, got through 3 years of a degree before kids interfered, was mildly interested in career prospects but very relieved to realize that I could fully support her, was mildly interested in the subject matter
Had my wife taken another year to become pregnant, she'd have graduated. That would put her in your statistic as a woman who graduated but didn't end up in the field. As it is, she's in the "women who drop out of computer science" group, usually assumed to have been pushed out somehow.
Actually graduating and having a career was kind of a "Plan B" thing, although my wife wasn't quite as deliberate as that other woman.
I met another woman who dropped the career about a year after graduating in computer science from a near-top school. She went on leave to have a baby, then simply stayed home. She didn't need the money, so why be away from the adorable little baby?
These women don't have the values that you evidently have. They aren't being pushed out. They are being pulled away by things that they value more. They don't have to comply with your value system.
Please stop blaming the pipeline for the difference. Interested, qualified women are being pushed away from the field by bias and attrition, and that's a problem we should be trying to solve.