Am I being unreasonable feeling a little miffed by the guy in front of me asking if he could close one of my three blinds?
The flight left at 18.20 hrs, it was a 777, six seats if F, and I was enjoying the bright and open seat space. However, immediately the seat belt sign was off the guy closed his blinds before he asked me.

My instant reply was "of course, feel free", and indeed he did.
Then I felt that "my space" was darker and not just as nice. In reality, I wish I had said to leave it as it was for the moment, especially with it being so early in the evening. I would not have been bothered had it been later on by a couple of hours. As it was I'd have felt selfish to say no when I did after all have three windows. But then so did he (that's my reverse logic) and I did not ask him to keep one of his open for my benefit
I have not had this happen to me before and I don't know if I would be so obliging the next time. I just don't like being put on the spot, I guess.

Tough spot. He's certainly entitled to ask you, although I think I'd prefer not to be asked to begin with, just like you. In a perfect world he should've just worn the eye shades. That's what they're for.

Were your windows the only ones open in the cabin? If not, then I think it's a bizarre request. Because I find in the F cabin, it really doesn't make a difference if the person in front/behind has 2 or 3 windows open - it's kinda the same. The light reflects much more off the ceiling. Same thing if you're in say 1A, if the guy in 1K has all his windows open you're still going to notice it even in 1A, because it reflects around inside the cabin and throw that window in the D seat. As for the person sitting behind you, their window light doesn't really penetrate the side of the seat, unless maybe the sun was at such an angle that it was somehow reflecting into the front of his seat?

Only one other person in the (full) cabin had two of their shades down. You are correct about the angle and I could not see how my light affected him at all. There was as much, if not more, light coming across from the other side.
Who knows?? As you say, a little bizarre
Wait till the next time

I find that when seating in 1k, the light from the first window in 2k will slip through the gap between the side-wall of the plane and the divider and it is really contrasting when all the blinder in 1k is shut.
If there is no one in 2k i will shut it as well (to give an idea of how close it is to the 1k seat - i can reach and shut it from my seat through the gap). But if someone is in 2k i will just put the cushion to block the gap.
I have never sit in 1A of 773ER but i suppose it will be the same as well.

I would guess you were departing LHR. I normally don't have a problem sleeping on the evening departures from London but I have found that if the windows are open I psychologically find it more difficult to sleep even with eye shades on. So I'm not surprised that someone asked to close as many blinds as possible.

Yep, it was the 18.20 LHR-HKG flight. I really understand how some do want to sleep, even at that hour, it's not my call whatsoever. I can also understand how it is difficult to sleep with eye shades on. I'd just never ask, nor expect anyone else to close their blinds for me. I would, and have, just got on with it.
Cushions seem to do the trick as LchChester says. Rather than put someone all wrong

Well, at least you weren't awakened by the FA to close the blind like the one that happened to a family member on AA business cabin.

This is a terrible incident. The OP is entitled to compensation.

Yes. He asked you. Feel free to say no (nicely). If he had simply closed one of your blinds, then it's time to feel miffed (and reopen the blind on your window).

When I take that flight I go straight to sleep as in my mind its already middle of the night in Hong Kong, I wouldnt go out of my way to ask you to close the shades as for sure it wont be too long before its dark outside even mid summer.

I was in 2A the other day, and someone from 1A just closed my blind through the divider gap. I didn't say anything and just let it go.

That happened to me on a DFW-NRT AA 777 in first class. Quite disappointing.