u/Zackkck

His love for Atreus didn't go away after Broks 2nd death. It's still there, and is especially seen when he was gonna attack Thrud to defend Atreus from her

Who he was, didn't just go away completely when Brok died. And his relationship with Atreus wasn't one sided either.

Atreus wasn't a perfect partner to Sindri during ragnarok, but he was still a good person to him. He listened to him, and gave him advice when he talked about Brok's 1st death. Showed appreciation for his support in both games. He listened to his troubles about Brok in gow2018, supported him through it, and even help save him from the mountain dragon. He admitted fault and apologized to him during 2018 after being a dick to him, and admitted fault and apologized for losing control on him, and running away to Asgard. He even talks with him just to enjoy his company, and learn about him, in both games

It's also worth mentioning that Sindri gave his support on his own, without anyone forcing him to. I also wanna say that Atreus is still 15yrs old; he's literally still a kid, while Sindri is over 200. At the end of the day, Brok's 2nd death really wasn't Atreus' fault. They were all fooled by Odin

If he can make up with his brother after them creating and giving Mjolnir to Odin, I think he can do so with Atreus. Especially since Atreus kept trying to mend his relationship with him after Brok died

Semi related tangent; while Kratos and Sindri weren't super close like with their other relationships, they still trust each other. Sindri was a good friend of Faye, and trusted her to do good with the Axe he and his brother made for her. And after everything in Ragnarok, he definitely trusts Kratos with the Axe to do the same. Same with the Spear. He also trusts Kratos to be a good father to Faye's son

Kratos in turn, also trusts Sindri with all the smith work he does for him and the team, as well as trust Sindri as an uncle figure to his son, despite his disapproval over the secrecy that happened in the beginning of ragnarok. He saw him as family.