well u do know Termina wasn't technically a REAL place like hyrule. It was in another dimension/dream world/lost reality/realm/ etc... actually everything u said adds to my theory, because he did lose his friend. maybe him reconnecting the world of termina and everyone with each other was his way of reconecting himself and opening himself back up to reality...
Termina is a parallel dimension. It is there as a physical world, it just doesn't exist in the same reality as Hyrule. It isn't a dream world.
How does anything I said add to your theory? Becaus he lost his friend? I'm gonna quote you again:
its not like it was based around navi being lost...
Suddenly you seem to think Link looking for Navi is a lot more important than when you repsonded to TheBlueReptile.
The whole Navi thing is extremely important and does poke massive holes in your theory. Link was looking for Navi, showing he already valued friendship greatly. Link taught that to Termina as a whole and then left, having learnt nothing new himself. Your theory is that Majora's Mask was a journey of self discovery. If that's the case then Link would have learnt something, which he didn't. If that was the case, Link would have realised the value of friendship the way the Skull Kid does and
then gone in search of Navi, having a newfound appreciation of friendship.
Nothing I said supports your theory in any way.
The skull kid could be his "split crazy personality manifesting itself in a dream or something"
Your entire theory is built on the assumption that after Ocarina of Time, Link's mind was in a state of emotional turmoil. Right here you suggested he had specific mental health issues, like schizophrenia. You say Link's mind was so messed up that it 'invented' the adventure in Termina as a means of fixing itself. Sounds like he must have gone plum crazy.
The background to Majora's Mask directly contradicts this. We know Link did three things between Zelda sending him back in time and him entering Termina.
1) Link visited Hyrule Castle to inform Zelda about Ganondorf. It makes the most sense that he would have done this immediately after he left the Temple of Time, as seen in the final cutscene in Ocarina of Time. Zelda mentions that he spent a few days there and she gives him the Ocarina of Time and teaches him the Song of Time.
2) Link went to Lon Lon Ranch where he met and bonded with a young Epona and perhaps bought her from the ranch. Link never lost rupees when he went back through time in Ocarina of Time so he may have still have a full wallet to do this. Regardless of how, Link got Epona.
3) Link rode into the Lost Woods to find Navi. Since she is a fairy from the forest, it seems like a sensible decision to look for Navi there.
These do not sound like the actions of someone whose mind is as damaged as you suggest. These actions are very deliberate, they are very sensible and clever, they show a clear system of prioritising and show he understands what Hyrule needs as well as what he needs for his own little quest. If he truly was in the state of mind you suggest, he would barely have gotten to the 'warn Zelda' stage.
I just disagree with your theory. I know it sounds like I am attacking it but I'm just trying to show why I don't agree with it. I've added this extra bit to try to help you see how nothing I said backs you up and that by saying that you're just not accepting there are flaws in your theory. There are flaws in every theory, don't take it to heart.