sb's rock

be someone's rock (be supportive; help someone through a difficult time) — быть опорой кому-л.; ≈ за кем-л. как за каменной стеной

Example 1: She says Bill has been her rock and she can't live without him. She’d be lost without him.

Example 2: When I was going through my divorce, my sister was my rock. She always listened to me and comforted me. (EB)

Example 3: Through it all, her older sister was Ann's rock. She took care of her, offered her support, and prayed with and for her. Without her and the rest of his family, Ann wouldn't have made it.

Example 4: Daniel, you know, he was more than a son to her. They were great friends, best friends and, you know, Daniel was her rock. So, everything that she's gone through Daniel's been there with her. And, you know, honestly I don't know how we're going to get through this. (Interview With Howard K. Stern, CNN_King)

Example 5: Dan told me today that she was his rock. And more important than any of his TV appearances or his great career, the most important thing to him was his unwavering love for her. (MSNBC_Cosby, 2005)

Example 6: Growing up, Yette led a very happy childhood, and she credits this to her loving family. She says her family has been her rock, and they are the reason she has such a healthy and positive outlook on her life. "You would really have to meet my family to understand the person that I am," said Yette. "My family has always accepted me and made me feel like them. I'm Cel to them, and they've always treated me just like anyone else." As a result of her strong family roots, Yette also has a lot of self-determination and ambition." (Born without arms, Virginia woman turns life's challenges into achievements)

Example 7: He proved to be her rock. When she lost her hair to chemo, he shaved his head, too. When she cheated on him with Richard, he not only forgave her, but also escorted her back home. What we learned from Smith: beauty isn't always just skin-deep. (Chicago Sun-Times)

Related vocabulary:
[tower of strength]
[как за каменной стеной]