Even though the experts say snakes can go months without food, doesn't mean it is healthy for them - unless they are obese. I still believe that there has to be a reason for refusing to eat. Like, temperatures too cold, moved to new enclosure or house, sick, injured, too much handling, whatever.
Temperature & their environment seem to play a huge part in snakes not eating. Even if you have your heatmat at correct temperature, doesn't mean your snake is warm. He spends time in his cool end he gets too cool and may refuse to eat. His warm end might be 30c, but if you have him in air conditioned room, his cool end could be as low as 25 or 20c.
Environment - put into new enclosure, enclosure too big, no or not enough hides can all stress your snake. Not only is it scarey for your little friends, the temps gradient from one end to the other can be overhwhelming for little snakes. When I sell babies I sell them established feeding, in their tub that they know, and with their hide box. When I upgrade their click clack to a bigger size, I keep their same bedding, bowls and hides so they still have some familiar smells with them. I don't know if this helps them, but so far I have not had any problem feeders due to going into new enclosures and I don't really want to find out if my methods are feasible or crap. A happy snake keeps me happy.
Also, picking the right time of the day can make a big difference too. Nocturnal animals come out to feed at night time, diurnal animals feed during the day. Stick with your animals clock and it might just be the problem. Most of my snakes are not fussy. My olives would eat at 2am in the morning, during shed, they don't care. Four of my carpets will eat anytime of day, but two of them only eat in the evenings. Doesn't matter if my lights are blaring, they will not eat during the day but come night, they will take food after refusing early on that day. Every snake is individual.
Last thing we want is for our animals to get sick. If in doubt, ring a reptile orientated vet. Most often, ordinary vets who have no interest or experience with reptiles are just a waste of money. So find the right vet BEFORE problems strike so that your friend isn't suffering while waiting to find someone to help.