Can Anybody Please Tell Me How To Write I Love You In Celtic?

Irish is a Celtic language. The other Celtic languages are Scots Gaelic, Manx, Welsh, Breton and Cornish. Irish, Scots Gaelic and Manx form the Q-Celtic or Goidelic branch of the Celtic language family. Welsh, Cornish and Breton form the P-Celtic or Brythonic branch.
 
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Irish   : Taim I' ngra leat
Irish/Gaelic      : T'a gr'a agam dhuit
 

Using celtic letters you might write I love you like the Attached picture.
As far as it is known there was no letter that corresponds to  a "Y" so I used the symbol for the letter "N" because it looks like a "Y">