The phrase "mutually fulfilling" is correct and usable in written English.
You can use it when referring to two parties or individuals that benefit from a shared interest or experience. For example, "Their marriage was a mutually fulfilling union, bringing happiness and success to both partners."
We worked around this and have had a mutually fulfilling sex life.
The cares of life are forgotten in a relaxed, mutually fulfilling utopia of pleasure.
The mentor relationship, which is so well exemplified here, shows itself as a mutually fulfilling one.
The right to divorce is deeply ingrained in American culture precisely because so is the ideal of a mutually fulfilling marriage.
200 lady Eskimos all having a hot flush at the same time, whoah!' 'I used to go bell-ringing to meet boys, which is not a great preparation for a mutually fulfilling sex life, all that tugging, not good.
As a theologian (he was an ordained priest) he advanced the view, held by many humanists who followed, that Classical learning and Christian spirituality were not only compatible but also mutually fulfilling.
These perspectives deal with interactions and entanglement of technical artefacts with organizations/institutions, actors, structures, and social practices within societies that mutually fulfill social functions [cf. 9].
And then, well, I do exactly what you'd imagine until the machine and I mutually fulfill our objectives.
More than a nice PR gesture, the message hit me with the force of revelation, as if all those years there'd been an unspoken covenant between me and my adopted city, my chosen family of friends, and now, finally, it was explicitly stated, mutually fulfilled.
Future studies should focus on the other important factors that are applicable to the assessment of the value of biodiversity conservation in socio-ecological systems, where society and nature are mutually capable of fulfilling their roles.
While I agree it would be wonderful to be in a relationship, it would need to be mutually nurturing and fulfilling.
