Being okay with letting food go to waste?

So I live with my sis and bro in law right now. We eat at home most nights and often have leftovers. Alot of the times, these leftovers are just left in the fridge, forgotten or too much to finish. But each time I see leftovers start getting old, I feel almost a sense of responsibility to start eating it or else it goes bad. No one else is interested in eating it, but when I bring up how we should finish it soon, no one wants to eat it still. When I bring up tossing it or eating it after about a week of it sitting untouched in the fridge, no one wants to eat it but also no one thinks it should be tossed yet. How do I get over this feeling?