As the time for mating comes, the males will approach the females and extend an invitation to mate. That's exactly what this pair of yellow butterflies accomplished.
Typically, butterflies mate with each other back to back. Not in a wide open space, but in the bushes, a little shielded by the leaves.
Perhaps they do it to avoid predators, or perhaps it's just that they're shy. To be sure, they each have their own reasons for this.
That species of butterfly is Eurema senegalensis . It is a yellow butterfly belonging to the family Pieridae, commonly known as the forest grass yellow. Typically spotted in bushes, it perches backward behind leaves.
All of the images here are my own work, taken with Xiaomi POCO NFC smartphone and an assembled external macro lens.