Happy nameday my dear Nikos! With love, Marina → Χρόνια πολλά, αγαπημένε μου Νίκο! Με αγάπη, Μαρίνα

[pouli]

Happy nameday my dear Nikos! With love, Marina.

[banned8]

Χρόνια πολλά, αγαπητέ μου Νίκο! Με αγάπη, Μαρίνα.

You could also use "αγαπημένε μου Νίκο" (Nikos, my love), which is a bit stronger.

[pouli]

Thank very much! I just started learning Greek, and cannot build phrases correctly. This way I would like to make a surprise to the person I love a lot.

[banned8]

In that case ("the person I love a lot"), go for the latter option:

Χρόνια πολλά, αγαπημένε μου Νίκο! Με αγάπη, Μαρίνα.