To make meatballs, mix together beef, bread crumbs, Romano, half of garlic, the egg, 1/4 teaspoon of salt, and 1/4 teaspoon of pepper in large bowl until well combined. With damp hands, shape mixture into 30 1 inch meatballs.
Spray large nonstick skillet with nonstick spray and set over medium-high heat. Cook meatballs, in two batches, until browned on all sides, about 4 minutes. Transfer to plate.
To make tomato sauce, heat oil in large saucepan over medium-high heat. Add onion, remaining garlic, and the oregano and cook, stirring occasionally, until onion begins to soften, about 3 minutes. Stir in tomatoes with their juice and remaining 1/4 teaspoon salt and 1/8 teaspoon pepper and bring to a boil.
Reduce heat and simmer, covered, 10 minutes. Add meatballs and return to simmer. Cook partially covered, stirring occasionally, until meatballs are cooked through and sauce is thickened, about 20 minutes.
Meanwhile, cook spaghetti according to package directions, omitting salt if desired and drain well.
Divide pasta evenly among 6 shallow bowls and top evenly with meatballs and sauce.