Even married people are concerned with leftovers spoiling (even people who co-habitate, but we’re not going to get into that). We don’t think there are any sites that list information on spoiling rates on a food-by-food basis – first, because of legal liability issues; second, because there are variables in how long different foods stays fresh, edible, and palatable; and finally, because the doorkeepers of the food safety world want you to be very willing to throw food away before it gets near spoiling.
The US government, through the Department of Agriculture and the Food & Drug Administration, is very concerned about helping people store and cook their food properly. They offer quite a number of online resources as well as pamphlets on food safety, but again, nothing comprehensive encompassing all the different foods.
Here are the general rules put forward by the government: Between 40°F and 140°F (5°C and 60°C) bacteria multiply rapidly, so food should not linger in that temperature range. It should either be in the refrigerator, freezer, or oven. It should not be out for more than two hours (one hour if the air temperature is above 90°F). Don’t keep food if it’s been standing out for more than two hours. Don’t taste test it, either. Date leftovers so they can be used within a safe time. Generally, they remain safe when refrigerated for three to five days. If in doubt, throw it out. It’s best if you store leftovers in a plastic container that can be sealed tightly.
Reheat foods thoroughly to 165°F (75°C), or until hot and steaming. Bring gravy or sauce to a rolling boil. Place carved meat or poultry in a casserole. If desired, sprinkle with broth to keep it moist. Cover the dish and reheat in an oven set no lower than 325°F (160°C) or a microwave oven.
Beyond that, use your common sense and do what cooks have done for centuries – how does the food smell and how does it look? You can’t always see or smell that the food is good, but you can generally tell pretty quickly when it’s outlived its usefulness.