"Ο πατέρας μου την αγαπάει πολύ."
Μετάφραση:My father loves her a lot.
It is not a mistake to translate"My father loves her much", without "very", so it is not a mistake!!!
Here's how a dictionary (Genius E-J dictionary) explains the adverbial use of "much":
 Adverbial "much" is usually used in negative or interrogative sentences.
(EX) I don't like the picture much.
(EX) Do you see him much?
 When "much" is in assertive contexts, it is usually modified by "very" or "so".
(EX) I like the picture very much.
 But "much" can be used even in assertive sentences when the verbs combined with it are those like "admire", "appreciate", "prefer", "regret", or "surpass". When it is used this way, "much" should be put in a pre-verbal position.
(EX) I much prefer a dry wine.
(EX) I would much appreciate advice from moderators.
 "Much" can be used to modify some negative-sense adjectives like "annoyed", "confused" or "distressed". Positive-sense adjectives are modified by "very" or "very much" when they are used in assertive predicates, but they can be modified by "much" in the negative/interrogative sentences.
(EX) I was very pleased by what I saw there.
(EX) I was very much pleased by what I saw there.
(EX) I was not much pleased by what I saw there.
(EX) Were you much pleased by what you saw there?
So, I think that "My father loves her much" is incorrect. But maybe others will offer opinions, too.