I knew this would happen, I think I called this a few threads ago.
See, the thing is, Tsuredure is a manga of constantly flexing bands of tension. Usually in a romance, you must build, build, build up tension, then release it in a big confession or climax or whatever. Setup, and payoff. The problem is, in a serial manga, you don't want to pay off. If you pay off, your manga loses that tension that makes people read it, and essentially ends. So you have Nisekoi with its endless setup and whatnot, with a plateau of development, but that just gets boring. Tsuredure basically solves this by having a huge cast, all of them in flux. Each couple has moments of high and low tension, and by interweaving those Waka can keep the story interesting without having a firm expiration date on it. Some couples get together right away, others take time and have lots of drama. You need a mix of both cute, SoL couples and couples who are fighting to get together, full of tension, both to keep the story balanced and interesting.
This is essentially the climax for these two characters. Takano and Sugawara have been the couple with the most tension and anticipation since the start, but like I said, you can only pull it so far before it becomes dull instead of tense. Readers were on the verge of getting sick of them, so Waka is pulling the trigger and having these two get together, finally giving this story a conclusion, and letting the two fall into a "low tension" state. We'll see them in the future, being cute and having fun, but it won't be the same "CONFESS ALREADY" feeling of suspense.
But there always has to be a "high tension" storyline, and that's what Motoyama is looking to be. His story will be the emotional, dramatic one, now that Takano and Sugawara are reaching their resolution. Or at least that's the direction it seems the author is taking it. In other words, there always needs to be ONE dramatic storyline, one person miserable. Otherwise the whole thing falls apart.