This is partly a failure of feminism. the systems that would have protected her in the past are those that patriarchy set up to save young people from the folly of following their young unruly passions.
Left to their own devices (in the US white context) both young men and young women more often than not have terrible, awful and destructive taste in prospective mates. This is why there was a whole system in place to stop them. Eligible young women were surrounded by old dragons to keep the bounders and cads at bay and young men were subjected to whithering scrutiny. The precise mechanisms differed by class and region but the general system was the same. Marriage was the only real outlet for sexual fulfillment (or any kind of non-scandalous sex life) and both young women and men had to prove themselves worthy of entering into it.
Of course this created victims, especially among those who were able to outsmart their keepers and the most pitiable cases were women (who could find that following that dashing, exciting man led to destitution and social exile once he disappeared as he usually did).
A big problem of feminism is that it never evolved past the victim mentality and often failed to see the big picture. Feminists rightly saw the injustice of the previous systems but never saw past that to the bigger picture, including the sad fact that lots of people, especially young adults don’t necessarily have good judgement. They fought for sexual emancipation which sounds nice, but never thought about what that would mean for those without material, educational or social resources to fall back on when things go south.
Femimist sexual ethics tended to start and end with the idea that men are predators who prey on women and that women should be free to follow their hearts and baser urges. And that leads to things like a pregnant unmarried and probably unemployable 18 year old following a ‘fiance’ and finding herself utterly alone and dependent on him.
I’m not saying we necessarily want a return of the dragons but an unmarried pregnant 18 year old with no social network completely dependent on a man with no legal obligation to her is probably not what feminists had in mind when they twirtle about ‘smashing patriarchy’ but it is a real world result.
You’ll notice I write about feminism in the past tense. It’s dead. No one needs anything that modern feminism is offering. Let’s put the poor beast out of its misery and build something new which balances sexual freedom with sexual and social responsibility.