Question with regards to facebook?

[Ƹ̴Ӂ̴ƷOrangeLollipopƸ̴Ӂ̴Ʒ]

Okay so on facebook I sent a message to someone (my bf) he only goes on facebook on the weekends so I sent him the message early because im a lazy person and so he can just read it when he gets on.
ANYWAYS my question is has the message been read or not read yet? Because at one point it tells me the message has been read then it says that it hasn't been read either an hour later or a few seconds later.
Then the next day it will say its been read again or the next 2 days. Im getting so confused at facebook right now (@.@)

[pri✍]

After we read a message, the sender will see "Seen at"; but if then we click Mark as Unread (either at/in Actions, or click the "o" at the right of the sender name on the left column) that "Seen at" will vanish.

So that was obviously happened.