It is the natural order of things in many ways. This question hasn't changed since the stone age. If you're male you risk impregnating, and you can, if society gives you that freedom, leave. If you're female you can get pregnant and you have no guarantee that the guy won't leave.
We love talking about personalities and you can always blindly insist that this issue is squarely on the shoulders of the couple in question, but we have come a way to mitigate the circumstances. Women can get abortions that are fairly safe, and if they want to have a kid they can get various forms of support as well, so it's a decision you can live with.
As for the guy, put the question this way. If the guy very reluctantly agrees to stick around and form a family, but it completely goes against his values and identity, is it better for him to stick around, be a wife beater, abuse the kid? Or would it have been better if he just left? There will always be cases where someone isn't fit to be a parent or it conflicts so much with his identity that it would have been better not to go there.
Either way he'll be judged harshly. Like a guy that stood by and let someone suffer when he could have helped.