I would have preferred Ayu to spell it "talking to myself." Maybe she spelled it like "talkin' 2 myself" for artistic creativity?

She might have spelled it that way to represent the style of the song (genre and/or lyrics).

My friend was asking me why Ayu and Hikki didn't spell their titles with the "-ing." He asked, "Why don't they spell it like 'Starting'?!

"
EDIT: Now that I think about it (

), I like both "talking to myself" and "talkin' 2 myself." They both have their own charms.
I like grammar so much that I compare different ways of writing the same phrase/sentence.