I think this song really suit for those couples who have being together many years and the passion and strong affection have slowly faded.
Research showed that the hormone that make us feel the affection or so called fall in love feeling only last for 18 months. After that, it's all how you maintain your relationship with your own efforts.
However, that doesn't mean you need put much efforts to maintain. Actually, there are many simple and little things that couples always forget to do after many years. Mostly because both are too comfy with each other and get used to his/her existence.
Simple things like..kiss on the lips, body contact, find new mutual interest, have an adventure together, spend times by just walking the in park....etc. There are many things can spark the chemistry between you and your lover again!! Who says once the hormone drops, you can't raise it up again??
Find some times to think about, like the lyrics "After all our trials, Maybe that is how I knew you were the one..." Remember back how you saw your lover as the Right one in the first place.
Gay relationship also the same, just depends how you think the relationship is...
Sweet couple!! =)