Formal:
* "Amo-te para sempre" (I love you forever) - This is the most common and straightforward way to say it.
* "O meu amor é eterno" (My love is eternal) - This emphasizes the lasting nature of the love.
Informal:
* "Te amo para sempre" (I love you forever) - This is a more casual and affectionate way to say it.
* "Amo-te eternamente" (I love you eternally) - This is another option, emphasizing the eternal nature of the love.
* "Meu amor eterno" (My eternal love) - This is a more poetic and heartfelt way to express love.
Other options:
* "O nosso amor é para sempre" (Our love is forever) - This emphasizes the shared nature of the love.
* "Para sempre teu(a)" (Forever yours) - This is a more romantic and intimate way to say it.
Ultimately, the best way to say "love always" in Portuguese depends on your relationship with the person you are speaking to and the tone you want to convey.