Answer:
It is not a complete sentence, but a dependent/subordinate clause of a complex sentence.
Step-by-step explanation:
A complex Sentence has one independent clause and at least one dependent clause. The two clauses are usually joined by a comma and or a subordinate conjunction (after, although, as if, because, before, lest, though, whenever, whereas, while, and some others)
Independent clause is complete in its sense and meaning - it can stand on its own as a sentence.
A dependent clause is incomplete in offering the complete meaning and it cannot stand on its own as a sentence. It offers partial meaning. The meaning becomes clear only with the help of some more information through an independent clause.
Since the clause "because I love chocolate" does not offer a complete sense, it is a dependent or sub-ordinate clause.