Boyfriend [23M] is upset that he [24M] didn't get a gift at me and my brother's birthday [23F/M, twins]

Boyfriend's age is 24, not 23. Sorry for title confusion.
I wish I was making this up. Last week was our birthday and our big brother [30M] gave us a matching male-female watch set. The set is probably worth around $2000 (so $1000 each).
My boyfriend and I have been together for a year and this is the first time he's said something that has totally leaves me in shock. He said this was an inappropriate gift to give to siblings as matching watches are worn by couples. He thinks the appropriate thing for my big brother to do was to give me a matching male-female watch set so that me and my boyfriend can wear them together, and giving a male-female watch set to my brother too, so that he and his girlfriend can wear them together. He even says he could get half as expensive watches so that overall cost remains the same. Or just pick watches that weren't matching.
So I asked him if he seriously thinks my brother should have given him a watch, on my birthday?! He thinks with the kind of gift that my brother gave me, that was the appropriate thing to do.
And he said he'd appreciates it if my brother and I wouldn't wear these watches to the same event. He's even upset that we posted a picture together on Facebook wearing and showing the watches. He thinks it gives a "we're a couple vibe."
I'm out of words to he honest. Is he being silly/stupid/immature/jealous or is there something here that I'm missing?

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tl;dr: Boyfriend thinks it's inappropriate that my older brother bought a matching watch set for me and my twin brother for our birthday. He thinks he should have got a matching set because it's what couples wear, not siblings.


Source.