Suppose someone broke into your house and ate the food you had made. (a real happening) And to express how much the whole thing has surprised you, you use a sentence like
Why would someone break into my house and eat the food I made.
Why would someone break into my house and eat the food I had made.
In this case, what's the difference in the meaning of both these sentences?
Both are correct, but in this specific situation, the difference is almost irrelevant because the major point of the sentence is someone broke in.
It really doesn't matter when you made the food unless you are trying to make a point about that as well. In which case, you would say something like:
Someone broke in and at the food I just made.
Most people would say the first though.
Both sentences are correct, but there is a subtle difference when you add the word 'had'.
Why would someone break into my house and eat the food I made.
This is something that you are commenting on that is either currently happening, or had just finished happening. Example, you walk into your house with your friend and notice the person eating. At this point, you turn to your friend and the sentence above is what you would say.
Why would someone break into my house and eat the food I had made.
In this sentence, you are talking about something that happened a while ago. Not immediately. For example, you would use this sentence the next day.
The difference is how to express the length of time.
However, this difference is too subtle and subjective to the the perception of time. A day for one person could be eons, but a very recent even for others. So it comes down to style and preference.
