I don't really have any suggestions, but dd was 4 weeks early and she would wake, like clockwork every three hours or less during the night. Feeding, (roughly) at 6am, 9am, 12pm, 3pm, 6pm, 9pm, 12am, 3pm etc etc
I don't know if being prem had anything to do with it, but I eventuall found out that she liked to be swaddled, this sometimes gave me an extra hour or so.
DH would get up and help until he started work, but that was on my insistence. I wasn't having him knackered for work.
I don't know if there is a great deal you can do at this age, but I found adjusting MY sleep patterns made a difference. Make sure your friend is napping or at least resting when her ds is. This makes so much difference. DD would wake at 6, feed then we would both go back to bed until the next feed...it really did help.
When dd had her night feed at around 9, I went to bed instead of staying up til the 11.30/12o/c feed, (before dd came along, I always used to go to bed late, so thought I would wait till last feed of the night, but it didn't stay like that for very long!) small things like that made all the difference.
I must admit that I failed miserably at the breast feeding, tbh the special care nurse put me off to start with & dd wasn't getting what she needed. (she was only 4lb 4oz) so we had to put her on a special build up milk, so eventually had no choice to ff, but feel it did dd no harm.
She will feel guilty, but then she is still hormonal in all of this. Guilt, I found tends to go hand in hand with child rearing, there is always something!