Junpaku no Wedding Dress de Fukushuu wo

Saki was looking forward to her wedding to her fiancé, Riku. However, when Saki returned from a business trip and opened the closet to put away the suit she had taken off, she found that the dress she had saved was missing! It's an important dress... Saki had a bad feeling about this, so she contacted Riku, and he told her, "I lent it to Ai, who is getting married today." Why is his childhood friend going to wear my big wedding dress?! (Source: Kadokawa, translated)