We never provided any evidence of our relationship, at the end of the day it is a visit visa, but I guess any additional evidence can help them make a decision.
We did however have matching dates in our passports for travelling together to Hong Kong and also when we worked together abroad.
In fact a trip to Hong Kong from Manila/Cebu is a very easy way of gaining evidence if your with your other half, as its very cheap with cebu pacific and only an hours flight.
