A group of three doors can be handled a few ways. With cabinets with finished ends, the doors at the ends should be hinged on the ends. For example...if it is a lone cabinet, and both ends are finished, the end doors will be opened from the inside out (as if they were a pair). The center door can be hinged either way.
There's no hard and fast rules for how to hang doors. Sometimes it's done with aesthetics in mind. They could be all hinged on the same side, or there could be a pair, and an odd one. The arrangement may have some bearing on what's going on with the base cabinet below (if any). Or, whatever is appropriate for convenience.