To find proof as to whether he is "in love" or not, Yukimura pats Himuro on the head from point-blank range. Seeing this, Ibarada, an upperclassman in the Ikeda Lab, talks about the need for a control experiment. In other words, in order to prove that the racing of his heart is because of Himuro specifically and not just because he's facing a woman, Yukimura has to pat Kanade and Ibarada on the head too. Himuro, on the other hand, sets out to prove that food made with love tastes better and cooks, but...
so how do you prove that 
mutual love is present?
لذا كيف يمكنكما إثبات أنّ هذا الحبّ المتبادل موجود؟
Wie wollt ihr da also beweisen,
ob ihr euch ernsthaft lieb habt?
así que , ¿cómo probarán que hay amor?
así que, ¿cómo probaréis
el enamoramiento?
Et comment prouver
la réciprocité des sentiments ?
quindi come potete provare
 che ci sia amore reciproco?
então como vão provar
que há amor mútuo?
И как вы докажете 
существование взаимной любви?