Betrayal of the heart

"Is there anything else you would like?" He asked gently. His voice was soothing and alluring, make her heart feel like she was in a race. 

She shook her head with her cheeks flushing. "N-no." 

He nodded, then waited for the sales lady to bring the necklaces. 

Once they were brought, he held up a fiery red ruby necklace and placed it around her neck. "It looks so beautiful on you. It accentuates the color of your eyes." 

"Thank you." She touched the necklace as her eyes fluttered. They both knew that he was merely doing it to look like a real boyfriend. Why was she so flustered by his actions? 

The main point was, the man she loved was Xingyu. Why was she so flustered under another man's fluttery? Why was her heart betraying her?