"Ty" vs. "Ti"

My girlfriend (from Chihuahua, Mexico) always spells "ti" as "ty". Often used in "Pensando en Ty". Is this common, and is there any difference in the meaning between the two? I'm always afraid to reply using that spelling.

Thanks.

Hi!
"Ty" doesn't exist. The right spelling is "ti". Might your friend writes it like that because of the new tendency to make variations in the spelling of words, such us, "x" meaning "for" or "2" standing for "too".

Thanks for taking time to answer, and for confirming that it is just a misspelling. (She also spells "sorry" as "sorri"). The "ty" spelling bothered me because I could not find reference to it anywhere. Thanks again.