Yeah, in MY case, and possibly all of yours, I think it has to do with short term memory. If you get too many ideas in a section of writing at once, and can't absorb the idea fast enough, etc... you lose connecting thoughts, and things start to get blurry.
1. The way I read is to decode and understand a sentence.(easy)(i.e., one person stole another persons car, took it to the store, and went shopping)
2. Absorb certain details about the sentence.(harder)(The persons were alice and fred. The store was ralphs. They picked up butter, bread, and a copy of business 2.0)
3. Connect those ideas with known ideas in long term memory.(easy)(I might remember fred because he is a friend of mine, or ralphs because I went there as a kid)
4. Connect those ideas with known ideas in short term memory.(including items in this text)(harder)(earlier the text said alice was the sister of one of freds friends, and that alice LOVES making her own garlic bread and was just reminded that she had no bread or butter at home.)
THAT is why you can read about relationships, get the plot, and understand the text but, when asked how a given person relates to it, may stumble.
Luckily, that isn't often quickly needed in the real world.
The brain(With regard to storing, recall, and reference) works almost like wikipedia is supposed to work, and AS people are GREAT with the long term links. I guess we're just not as good with the short term ones. 8-(