HB - condiments, most of them anyway, have some form of acid/vinegar in them. I've had BBQ sauce in my fridge for a year that is still good - but it's mostly vinegar. Two weeks for the spaghetti sauce I'd say is pushing it - there's stuff growing on the top that you don't even see yet.
"Count yourself...you ain't so many" - quote from Buck's Daddy
As soon as I typed out the question, the vinegar answer popped into my mind.
After all these years, I'm still having to remind Mr HB to wipe the top of the condiment jar with a wet paper towel so the stuff doesn't dry up and get yucky on the edge. That grosses me out completely.
If you are cooking and only use 1/2 jar of spaghetti sauce, in the future and with a new jar of spaghetti sauce, freeze the other half in a plastic container? (((don't misunderstand....Angie.....throw that one in the trash and buy a new one.....it's rotten)))
"I have not failed. I've just found 10,000 ways that won't work." --- Thomas Edison
Another vote for tossing it after a week. Everytime I open something - jarred salsa, pasta sauce, carton of chicken broth - I mark it with a pen as to the date I opened it.
Cartons of chicken broth - as per the carton instructions - are used, frozen, or tossed after 14 days. Same goes for salsa, which has a higher acid content than regular pasta sauce. Pasta sauce or plain tomato sauce goes out after a week.