I don't think they do. As confirmed par Sega, Silver and Blaze share a brother-sister relationship. They also confirmed that Sonic The Hedgehog 06 never happened and that it's "Sonic Rush" that's the true story behind Blaze. She is from another dimension, parallel to the time Sonic and the others live in while Silver is from the future. I'm not saying that Silvaze will never happen, but according to what Sega said, Blaze has plus chance of being with Sonic ou Shadow than with Silver, who is like a brother to her.
No. No characters belong with any other. Sonic is not a franchise to focus on romantic relationships. Furthermore, Silvaze is a detriment to Blaze and her character. Since Silver almost always dominates the scenes he and Blaze are featured in, it prevents Blaze from being her own character, seeming like a sidekick to him, which goes against everything she was in the Sonic Rush games. One might argue that she was essentially Sonic's sidekick in these games, but unlike with Silver, Sonic never completely overshadowed her, giving her a chance to stand out and have her own glory. Besides, Silvaze is a reminder of a game which most do not want to remember, and which is probably better left in the past and forgotten.
