I can explain

Xia Luna and Cheng Yu were both startled. 

Xia Luna turned robotically, her heart racing. "Lanni…" 

Lanni shifted her gaze between the two of them then she laughed. She walked over to the table and grabbed a bunch of keys. "I forgot my keys so I had to turn back. The interesting conversation I just overheard wasn't part of my business so… don't mind my interruption, please continue with your conversation." 

Cheng Yu had nothing to say as a retaliation against Lanni's mocking words. 

When she saw Lanni leave, Xia Luna anxiously grabbed her arm and pleaded. "Listen to me." 

"Let go of me." Lanni pulled her arm out of Xia Luna's with a fierce glare. 

"Lanni, don't… I can explain." 

"Explain?" Lanni scoffed. "What do you have to explain Xia Luna? I trusted you. I believed you even when the truth was right in front of me. How could I… I have been so stupid." The last part was meant to scold herself.