Re: unwanted pregnancy
TBH, a married couple should not be relying on barrier control contraceptives like condoms... it's one of the most rudimentary issues to discuss when you are in a long term relationship/cohabitating/married... i.e family planning, birth control... if times are tough then they should've thought of more secure means of contraception, like hormonal or intrauterine methods....
Oh well, it doesn't really matter now... does it? Whether their contraception malfunctioned or not is not the issue anymore.
I don't think he will resent her or the child. In all honesty, there will never be the "right time" to have a child (i'm too busy at work/i don't want to leave work/ i like my independance/ we're not secure financially) but when it does happen, everything just fits into place, and InshAllah, it will for your friend.
BTW, how many children do they already have? And how old are the couple, if you don't mind me asking?