Now that their first missions have been completed, Uranus and Neptune fade a bit in the series to give more time to Hotaru. The next episodes are mostly focused on their thoughts and feelings toward Moon and company as well as ties to their past lives.
When Tuxedo Kamen confronts the Outer Solar System Soldiers, he asks them why they will not join forces with Moon and company. To his surprise, Uranus frankly says, "They only get in our way…" Neptune elaborates with a more considerate explanation, "This battle… is too much for Sailor Moon…" The three soldiers feel that the battle against the Death Busters is more suitable for them to handle instead.
Some would say that Uranus was being cocky there, and she did give that front, but I believe she sincerely thinks it is best and like Neptune believes it would be too much for the five other soldiers to handle. All three of them wish to protect the others and not worry them when they find it unnecessary to. Alas, with how Haruka approaches such, it makes Sailor Moon and company curious and worry even more…
Haruka seems to forget is that while fighting outside invaders was the turf of the Outer Solar System Soldiers, she, Michiru and Setsuna are no longer in the past or the future. They are in the present and not fighting alone on the outer rims of the Solar System. What she also doesn't know is the power of full out teamwork. As Uranus, she displays it well with Neptune, but in all other cases she believes only in her own powers.
Perhaps it is because it was part of her personality, like how Michiru noted she never relied on anyone but herself. Then there is the facet of her past life as a lone soldier that couldn't rely on others.
They protect and care, but always at a distance.