Why are you not supposed to split the infinitive of a verb, for example: "To boldly go" should be "to go boldly." Why?
It is usual to follow the 'to' with the completed infinitive word. It is usual for adverbs to follow verbs. In this way there is no special emphasis given. Grammatically, it is not a problem in either case.
Sometimes sentences become very clumsy when infinitives are split e.g.
It is foolish to, in my humble opinion and in the opinion of many wiser persons than myself, tell a girl that you love her unless you truly mean it.