How to Find Fountain of Youth despite not siding neither Jiuli nor Melody House?

[Monochrome]

I think I ♥♥♥♥♥♥ up by not siding with Melody House at the camp.. how can I get into melody house to find the fountain?

[darkshintos]

Fight them. The event at the Deserted Courtyard is the only way to get the dialogue option to pass the guards. This is the case for both Melody and Jiuli.
Neither of them are needed for the Fountain of Youth though. You can ask any random melody member about the location, or you can just walk around and find it at the Melody House. Nothing changes if you asked someone or found it yourself.

Assuming you want to have neutral/good relationship with both and do their quests, you'll want to enter battle mode manually (button right of Meditate) outside the vision range of the guards. Don't enter their dialogue as you cannot retreat from that fight.
Walk past the guards in battle mode. They will aggro on you, but as long as you don't kill them and have enough movement range to escape (Put your mouse over the eye icon next to the speed button, you can Retreat anywhere outside the blue boundaries. Its based on any potential combatant's movement range), you can retreat and you will stay on the square you were at.
After you enter, you can gift the people there and raise your Relationships.
Then when you have enough Relationship (Like 60ish), you can manually fight and kill the 2 guards and when they respawn, they won't bother you anymore.

If you already have -10 Relationship with the sect/tribe, your only real option is to kill them, as you cannot mediate their Relationship.