Being a DV survivor so yep it happens to the best of us im afraid, i put up for 5 years untill a brush with death woke the pants off me up then realised! I have had a few friends that have & still going thro it & trust me if i cant make them see despite the shear reality of what i went thro. I have worked with womens aid & done media campaigns also did a course on behavioural psychology of victims & abusers thro them too, so do know what im talking about. The trouble is that as whats happening with your friends is that the mental emotional behaviourial has already happened & is the hardest to break, ie he hits me cos he loves me so much beleif which is implanted, usually these women have huge low self esteem beleive they are not worthy of owt else, they couldnt help it coupled with their BF promise of change which gives them renewed hope also with self blame cos they beleived they caused or deserved it!! This is not gender specific as men are victims from husband beating [DV** too & is based on same psychology also.
There is a huge campaign atm regarding domestic violence & there is going to be 2m invested in refuges & Dv centres.
All u can do is point them to womens aid services that can get them help & support to break free, Hyndburn have their own drop in centre u can pm me for details of that.
More info:
http://www.womensaid.org.uk