Why does it sound so good to my ears? The music theory explores that.
These are a few songs that include melodies that are just so... pleasing to my ears. If there is a heaven, I'll hear these when I get there.
Do you know any more?
Final Fantasy Prelude Vocal: https://youtu.be/4reZp854LZg
I'll be missing you: https://youtu.be/Z8jzHyy1YHY
Maroon 5's Pure imagination from 1min 50s: https://youtu.be/OTc3oyedCvA?t=1m50s