Blaaah it does sound possible that this wasnt an accident. It always surprises me how many people get pregnant "by accident" yet everyone i know who is actively trying for a baby takes months and months!
Maybe she is just saying adoption so she equally seems shocked etc and has no intention of adopting the baby.
Lots of girls do get pregnant deliberately and its very unfair on the fathers (not saying they all do so don't flame me but the OP has thought this and I do know lots of girls who have done it).
In his case, given that he doesnt seem to be overly into her, I would get him to explain his feelings, that he will always support her etc but can't guarantee he will be her long term partner (it may sound harsh but if thats how he feels its better for it to be out in the open). She may feel differently about her options once she knows the reality. They arfe both onlhy 17 so whilst they may thinking 'happy families' now, the reality is very few people are still with their childhood partners.
I understand your disappointment - i'd be gutted too.
I don't think the issue is about using a condom TheFallenMadonna, they had decided to opt for the pill - missing one (if she did) is her responsibility where that sounds harsh or not. Getting pregnant doing everything right is different.
If she does go down the abortion route (unlikely from what she said), the aftermath is not all doom and gloom, i know a good few people who have had them and have no regrets whatssoever. Its personal circumstances at the time