A commitment of two years flying good gear like Caravans and King Airs is not all that long if you are starting out, because the laws of supply and demand in PNG will look after you better than most places.
For example, once a pilot gets some PNG time and turbine time, provided he doesn't crash, become a screaming alcoholic or get an incurable dose of the clap, it is relatively easy up there to snag a job left seat Twin Otter or right seat on a Dash 8.
Once these initial hard yards are done and a pilot gets a command on at least a Twin Otter, nearly all operators offer FIFO of 28 on 28 off or similar. Because of the pilot turnover, such promotion comes quickly enough to those prepared to stick it out.
Until then, if you have a partner, she may need to get used to long separations because married accommodation in POM is not easy to find and it isn't much of a place for a female unless she can be doing something useful like medical work.
Whether you go to PNG depends on how much you want to fast-track your career, how much you like a bit of adventure along the way and whether you can endure a certain amount of celibacy. Though the latter is optional because the local girls are very accommodating - but see above warning about the clap.