Ich liebe dich Jakob would be the most formal/powerful way to write it.
For reference: Ich = I Liebe = Love Dich = You Jakob = Jacob
Ich liebe dich jacob OR jacob, Ich liebe dich. Ich liebe dich means I love you and then the name stays the same bc its a name. This sentence is one of the few that's structured exactly like the English sentence so it's up to you where you put the name.
In German, "I love you Jacob" translates to "Ich liebe dich, Jakob". This phrase uses informal language, suitable for intimate relationships. It indicates a close emotional connection between the speaker and Jacob.
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