How do you say i love you with all my heart in hawaiian?

Aloha: Ua papau koʻu na'au i ke aloha o 'oe [oo-ah papow ko oo na ow ee kay aloha o oy] This is literally "my whole heart is involved with the love of you".

Aloha au 'ia 'oe [...ow ee-ah oy] is actually 'I love you', but that would be a different concept in this case.