They were still sort of feeling things out, and that was okay. It would've been unrealistic to think that even after taking some time to heal that things would just bounce back like nothing had ever happened. That in of itself would just discredit the fact that they were both hurting and needing to heal, and that wouldn't be fair to them. But they both knew that the other was still vitally important to their lives, and they needed each other. Bucky needed his best friend, and he always would. Steve's words assured him that the feeling was mutual.
Although he was a little unsure if he'd be able to hear about Stark without feeling at least some pain in his heart, there was no way Bucky would know until they tried it. And he meant it when he said he was happy for Steve. He needed to be able to hear about that part of his life because he didn't want them to keep anything from each other anymore. That was exactly how they'd lost their chance to try to be together themselves, and though things had worked out the way they did and they were both happy, Bucky didn't want to make the same mistake and lose out on any aspect of their friendship.
"Sure," he said. "That'd be fine. Looks like they're already inseparable." He hadn't seen his Snubbull so happy since he'd brought him to town. Bucky felt compelled to say a little more, to tell Steve how happy he was to see him, that they were talking again. But he reined it in a little. Hopefully it'd show in his smile, and in the fact that they were going to see each other again in just a little while.