Almost perfect, but it has to be "dla ciebie" :)
I guess that 'dla' just needs this emphatic form 'ciebie', otherwise it sounds totally wrong.
„Dla Cię/cię” is not exactly wrong but it sounds archaic, as if the text was from 17th century.
Congratulations, couvertrash! I make mine your words!
Tak, Duo. Jestem tutaj dla ciebie. Będę z tobą na zawsze!
When would you say this? "Be with me" sounds a bit odd in English, except perhaps in church.
That sounds a bit strange to me, but I guess it could be a way of saying "I want us to be together (a couple)"?
Because even for Polish people, "z mną" would be very difficult to pronounce.
For sure if the first sound is: s, z, ś, ź, ż, rz, sz and then it's followed by another consonant. Also "ze mną", "ze mnie". And well, in some expressions that just simply evolved like that and would sound strange with "z" even it it was possible to pronounce them.