User blog comment:Mewkat14/Happy Valentines! Sonic Couples!/@comment-115265-20120218113312

Sonic CD, Amy's first appearance, was released a few weeks after Sonic SatAM started. I think Sonic and Sally's coupling existed (somewhat) before Sonic CD was released.

If this is the case, then that would make Sonic and Sally the first coupling in the franchise. Sonic and Amy would be the first couple in the games.