To your question of frogs and emotion, I think it's entirely possible they have some level of emotional expression. They definitely like being together, and they go out of their way to sit together quite often. Sometimes they'll sit nose to nose. π
Perhaps there are other reasons for choosing to be close to each other, such as sharing a sunny spot to get warm, yet there doesn't always appear to be a reason other than companionship.
I've also noticed over the years of having pet frogs, that some are more social than others, and that a frog may go through a period of preferring solitude, then switch to wanting companionship for an extended period. When there are multiple frogs living together, they will select the same companion repeatedly during that time. That part I found very interesting. Their seeming preference for several days, even weeks, for a steady companion, sitting together in various locations, but always together.
Jane Goodall should have studied frogs, too. Just sayin'.