Okay, no matter what her husband wants, this has to be her decision. He is not the one pulling out his breast every 2 hours or less in order to feed a hungry baby. He is not the one in pain.
However, that pain is not going to go away automatically because she stops. Actually, the best way to help with the blocked duct is to continue feeding and possibly add pumping (which you probably know).
My best advice is to say to your friend something like, "I know you are frustrated and really just want to give up right now. And if that is your final decision, I will support you wholeheartedly. However, before you do, why don't you try contacting this person (insert name of local La Leche League leader). They can help you see if there is something wrong with your babies latch. Also, they can help you work through the blocked ducts. You will need to do that whether you decide to continue or not. If after a couple of weeks with the help of this group, you are still having problems and want to quit, then that is your decision and I will support it wholeheartedly. I hate to see you quit now because of your frustration and lack of sleep. I don't want you to regret quitting down the line. Also, if you tell your husband this is what I am going to do, you will be giving him a compromise and yourself a chance to succeed. This might make quitting later easier on your marriage and less problematic because you will know how to deal with milk engorgement should it happen."
This keeps open the option to quit but also gives her a place to find help. You can find the name of the local La Leche League contact on their website. It may just be that she needs to talk through it with someone who understands. I know with my first I gave up after 6 weeks. I wish I would have known about our local La Leche League. My second was breastfed for about 1 1/2 years (with the help of our local Le Leche League). My third refused to breastfeed after having a supplemental bottle for jaundice (his jaundice was pretty bad). I still tried for over 6 weeks with my third and know that my decision was correct but I still wish he would have breastfed. I, also, know that some women love it and others hate it. If she hates it, then the bottle would probably be a better choice because she would be more relaxed and a relaxed healthy mom is important, too. But I would hate to see her give up over temporary frustrations.
Good luck. Hope this helps.