Kyoya has a perverted mind like any other man.
He was interested in Xaya's body naturally, then with the affection born out from their time together, Kyoya knew that his interest and love would never run out. However, there is a limit to his interest.
Since his first 'girlfriend' turned out to be a titty monster, Kyoya developed a high affection for breasts, his mind filled with various ideas that those peaks can be used during the night where things get hot!
Thus, Kyoya was fine for such perverted moves, but when it came to the feet, he was skeptical and rather against it. However, his wife wanted to try everything. Now that her feet felt superb, Xaya wanted to try massaging her husband with these two new kinds of weapons.