My experiences: Couldn't buy Cebu Pacific tickets online with a UK credit card (they revamped their website a few weeks ago and now you can) so they were reserved over the phone. No proof that I had a ticket out of the Phils. We were on our honeymoon, entering Phils via Singapore and leaving via Hong Kong, on different airlines. JetStar asked for proof of onward ticket whilst checking in at Singapore, which I didn't have - we had yet to reach the Phils to pick up the tickets, and JetStar's reservations computer doesn't talk to Cebu Pacific's, and the latter is in a different terminal at Singapore.
But JetStar were helpful and told me the cheapest way of getting around the restriction - buy a fully refundable ticket. I would have been out of pocket until the ticket was refunded, less an admin fee of about £10. But whilst I was booking on their computer, the agent noticed I had a Filipino passport with me (my wife's). He asked if I was married - yes. He asked if I had the marriage certificate - yes. Produced those and I satisfied the immigration restrictions and was free to board the plane.
Upon arrival at Manila immigration, no check was made for marriage or onward travel. But I stayed for only 2 weeks so didn't need anything special beyond a 21-day tourist visa.
Yes, the airlines are right to demand proof lest they incur an extra traveller back from whence they came, plus whatever fines they get, but if you had the proof (Balikbayan or not) then they should have let you on. So I think Cebu Pacific were wrong to demand a return ticket. It's a funny airline, sometimes you get great service on there, with no quibble changes and tiny admin fees for changes; yet other times they can be a PITA whilst you stand at a counter for hours whilst they do goodness knows what.
Geoff M.