Why is there a "は"?

I didn't thought the "は" was necessary, but imagine there must be some difference between 彼女と話ません (I do not talk WITH her) vs 彼女とは話ません (I do not talk TO her), right? Or are both the same thing?

I didn't thought the "は" was necessary, but imagine there must be some difference between 彼女と話ません (I do not talk WITH her) vs 彼女とは話ません (I do not talk TO her), right? Or are both the same thing?