Doppio Senso is a Manga/Manhwa/Manhua in english language, Adult series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

“What are you thinking about?”
“I’m thinking about a guy.”
KyungHyun stopped in the middle of a deep kiss and sighed. His lips began to form a smile, but his fierce glare said otherwise. Possessiveness and jealousy spread across his sculpted face.
“Will you tell me his name?”
His easygoing and languid voice reached her ears.
“Why?”
“So that I can shoot him down.”