[user104658]

If he thought she was on the pill and wanted to be using contraception then, no two ways about it, it's not great. Even worse would be if he had specifically said that he did NOT want kids.

IF he had previously wanted her to come off it / wanted children with her but she had previously said no, then her thinking is more understandable, as she would just have been assuming that he still wanted that and would be excited when she got pregnant.

However it would probably have been better to at least check that he was still on the same page before assuming and going ahead with it...