The problem is that we've not seen Hannah before she started this job, and the nature of the show demands that we don't see her too much anyway. As well as the fact that drama is a demand of TV. Showing her as a happy person isn't going to sell as well as a relationship crisis or her dad's found out about her job or whatever.

So we don't really know who Hannah would be. It's true that she probably has issues beyond that - who doesn't? But it's certainly not making things better. If nothing else it precludes any real long-term romantic relationship. Alex's reaction was pretty unremarkable, and if Ben had been with her when he found out you can bet he'd have done much the same. And whatever other problems she might have, genuine connection was something she clearly benefits from and wants. Despite her protestations in Season 1 the only time she seems genuinely happy rather than acting happy in her work is when she's more like Hannah (Like with the disabled kid).