Natasha's Display of Loyalty to Steve was Wonderful
In Civil War, the woman was pro-registration and she let Steve and Bucky go even though they weren't on the same side and she knew would get in trouble for letting them go. She made a choice between her head and her heart and it didn't come of as strange or out of character. If she truly cares about someone, damn the political agendas of the government. She will still find a way to keep them safe, even if it means putting herself on the line. Letting Steve go was an example of Natasha staying true to her word, which is parallel to when she asked Steve in TWS if he would trust her to save him, and she did. That conversation came full circle in Civil War and shows us just how much Natasha cares for Steve. This is a strong friendship they share and a beautiful example of true loyalty. For a spy who's used to only looking out for herself and keeping her cards close to her chest, this was a unique and special moment of character building for her. Even Steve was surprised that she let him go. I love her words to T'Challa. "I said I'd help you find them. I didn't say I'd help you catch them."
I also loved the fact that the first time we see her hug someone or show them true affection - no, that half-arsed, badly written fever dream, Brutasha, that Whedon threw at us in AoU does not count - she hugs Steve. When she said, "I didn't want you to be alone," it stabbed me in the heart. Even though she knew they would be on opposite sides, she wouldn't let their differing viewpoints stop her from comforting him. That was such a powerful moment for them, and it's one of the reasons I like the two of them together. Their relationship has grown so much stronger after TWS, and it's my top favourite out of all the MCU relationships, period. Simply beautiful!