The following contains spoilers for Season 2, Episode 6 of Science Fell in Love, So I Tried to Prove It, now streaming on Crunchyroll.
Despite sharing a genuinely romantic kiss back in Season 1 of Science Fell in Love, Himuro Ayame and Yukimura Shinya have spent all of Season 2 trying to determine if their love is genuine. For a time it seemed these two lovestruck but clueless young scientists would never make any real progress, but Ayame and Shinya have suddenly made an astonishing breakthrough.
In Episode 6, they agree to spend the day on a relatively normal date and make minimal use of lab equipment or formulas. To their delight, the two of them stumble upon the truth of their relationship -- which has been staring them in the face all along. Their love is indeed authentic, opening up more exciting possibilities going forward.
Ayame and her kuudere paramour Shinya enjoy their "normie" date, and later find themselves alone -- with remarkably good romantic ambiance. Ayame takes this chance to speak her mind and explain that just like Chris Florette and Suiu, she can only determine true love by listening to her heart and make an arbitrary declaration. In Episode 6, she tells Shinya "I love you" beyond all doubt.
Shinya needs a moment to process this, and before giving his response, he works out some calculations inspired by the simple but effective love formula he gave Kanade in a previous episode. Despite trying to handle this science-style, his calculations soon turn subjective and his passion for Ayame practically turns his project into a parody of itself. Shinya reciprocates by speaking semi-arbitrarily, and now understands that perfectly calculated love simply doesn't exist. His view now is that true love is found when A becomes cognizant of their love for B, but this doesn't end the experiments. In fact, the love experiments are sure to be bigger and better than ever going forward.
On one level, the mutually spoken "I love you" that evening marks the end of an era for Shinya and Ayame, and their fellow scientists Kanade, Ena and Kosuke all cheer for them. However, Kanade is wrong in presuming that the experiments are over and true love has been found. To everyone's shock, Ayame and Shinya explain that while the existence of their love is now proven, the extent of that love remains to be determined. They still have to quantify their mutual affection, and that calls for some experiments.
The way Shinya and Ayame put it, their love could be anything from the equivalent of "I love my favorite fruit" to "I love my friends" or "I love you, my soulmate." Love exists in degrees in their view, and they can't become a true couple until they can place their love somewhere conclusive on a gradient. While Kanade and the others find this anticlimactic, this development serves as a charming and clear signpost for Science Fell in Love's evolving plot.
Even if more experiments must be conducted, something has indeed been accomplished in Episode 6 -- and there's no going back now for Ayame and Shinya. No doubt they both hope their love proves to be soulmate-level and not just "I love strawberries" level, and this marks the beginning of the next great story arc for Science Fell in Love.