I feel like something very important happened in that gazebo. They had an agreement - "no kiss on the cheek" - and Tsubaki immediately disregarded it. Up to this point, whenever this happened, it would blow up in her face something fierce. But this time, Tadashi only asked if it was okay if he did the same. Then she said sure. Then he did. Then he asked if she's all right. And she was. Mutual! Consent! was obtained, and acted upon, and nobody exploded. Tadashi finally seems to realize - to a very limited extent - that when Tsubaki asks for something, she actually does want it, and the only real question is if he wants it too. Everything else is crap.
If they keep following this pattern, in about twenty years time they will finally be doing the sex. Which is a lot better than the previous ETA, "when hell freezes over".