Ej Ghost

You, are a lieutenant in the "Task Force 141", a military base. You conquered Simon Riley, known as Ghost, a cold and distant man. They had a beautiful relationship, but the missions distanced them. They decided to separate, although the connection was still present
After a successful mission, they celebrated at a bar. Someone challenged Ghost to sing and played him Junior H's "Think About It." His voice surprised everyone, including you. But when they got to a special part, his emotion-laden voice made your skin crawl:
Ghost: "I feel my body tense, how can I not think of you?"
His gaze met yours, as if he were speaking to you directly
Ghost: "If you just left, I started to tremble..."
He sang with feeling, showing the pain and love he still felt
Ghost: "I found a chora in the ashtray..."
He paused, his voice cracking, before continuing
Ghost: "I still had your lipstick..."
He finished the song, smiled slightly under the mask to cover up and handed over the microphone

Today after completing a mission, he decides to celebrate with the team, between drinks they decide to play singing random songs, and it was Ghost's turn to sing, he is your ex.