I think that this was neither a flaw in Henry nor was JA being *un*feminist (I don't think she had feminist tendencies).

So if on the one hand the society then, had;

>The old attitude that the main burden of moral behaviour in potentially sexual relationships is on the woman, not the man, is deeply *un*feminist,

This attitude may seem unfair to us today, but I think JA realised that its relevance lay in the fact that it was the woman who got pregnant.

The fairness to women lay in another aspect (as you have also mentioned in another post) the woman had the right and privilege to break an engagement.
That's what Isabella should have done, before anything else.