Yup, definitely from cohabbing. If you are wanting to breed, housing them together isn't the way to go. It can cause unneeded stress for both snakes, result in a premature breeding, and sometimes a male that is "in the mood" can harass a female to the point of illness. The constant stress of being bred/harassed can wear her down, causing her immune system to go lower and sickness to set in.
I say separate them, and follow normal breeding procedure, where the male/female are only together temporarily. This will most likely fix the males eating problems, and ensure that no other potentially deadly issues arise. Keeping your snakes together can result in some very nasty things including cannibalism, premature breeding (which cause lead to death), fights, and refusal to eat.
Also, many snakes will not go after a mouse that is not dangled. Some have to have it wiggled around so they strike and constrict it. Having a hot moving mouse in front of you is much more appetizing than a hot dead still one, you know? It just helps their hunting instincts to kick in. I say after separating them, wait a week and dangle a f/t or freshly killed mouse. If not, you can try washing the f/t mouse with dawn dish soap, scenting it with lizards or chicken broth, or just making it suuuuper duuuuper hot.
