So I see people complaining about the lyrics not feeling like they relate to Kingdom Hearts. Let me put a little perspective on earlier songs.
This is a song about two people still feeling insecure about their relationship together. The speaker has felt alone for a long time, and when they met this person it felt like some of that loneliness was leaving. The speaker feels like this person is their light that finds them when they are lost in the dark, and regardless of fearing having to take big steps like meeting each other's family or figure out their future, they decide that that should enjoy the moment with each other.
The meaning behind Simple & Clean is pretty similar to Hikari, if not a bit more straightforward about it.
This is a song about being nostalgic of the past. The speaker and the other person are moving forward with their lives and the speaker fears they will drift apart and begin to walk on different paths. They miss how happy they were together in the past and still love them deeply, so they look back to the past fondly. They remember the happy times where they could just be together, but they need so much more out of their relationship right now.
This is both similar and yet vastly different from Passion. The speaker feels like the other person is like a home or a safe haven to them, but also exactly the very thing that can break them apart. Even so, when the other sleeps those fear go away because they know at the end of the day they are together. No matter how many times the other person breaks them apart, they will be put back together again.
It's not a lot to work from, but this is a clear continuation from the previous themes.
This is about finally wanting to take THE big step in a relationship even with the lingering doubts. This is something of a culmination of the speaker's feelings since Hikari, especially since that was the early part of their relationship. The speaker still feels insecure, but they don't want to let that hold them back anymore. They want to be with this person forever. They don't think anybody needs to judge their relationship and there shouldn't be any expectations. All they need is the two of them and more of these days where they are being honest and open to each other.
Again, this is about taking that next huge step in a relationship. The speaker has wondered how they have been able to live with people who could lie to them and say things to them just to hurt them for so long when the answer has been there in front of them the whole time. This other person is exactly the person they want to spend forever with and when asked, of course they'd want to take this step. The speaker loves this person very much, but if the other person intends to hesitate about this even after asking, the speaker would rather be ignorant to it and just stay in this blissful moment.
It's a beautiful trilogy (hexalogy???) of songs. They all tie together. Early relationship fears, the difficult middle where anything can happen to hurt each other, and the final union.
And for people who are still upset even after this long-winded explanation and continue on the trite "but its a marriage song" argument, please remember this series has its main musical theme as "Dearly Beloved", the first thing the ordained minister says in a god damn wedding ceremony.
