I suppose Trystan is a male.
Into what language do you want the translation?
In Hindi it would be, Trystan mera pyaar, meri jaan.
But I prefer Sanskrit. A good translation into Sanskrit would be: Trystan, preSTho me praaNaashcha me. PreSTha is superlative of priya. Let me know if you want it in Devanagari or another Indic script.