Yes there was a chapter like that.. its missing?... not sure why though. But it didn't use to just jump to the wedding there was a part where Haru is sleeping in a Lab and Mitty goes to find him telling him he's gonna be late and then they get together with their friends.... but as they go off he asks her if they should get hitched when she was finished with her schooling and she says yes...
This is all missing..
I found it.. Its not an extra Chapter... its the Last part of Volume 12 .. Chapter 48.
Its there on KissManga... seems Mangago Cut off the pages of this chapter..
But you can read it all there... but still shame on Mangago.. why would you cut out this part.. its so sweet.
oh well.. I recommend reading it..
I cant find the chapter where he comes home and the one where she receives a ring (?) From him :((