Ownership of my senior researcher is claimed by both of the ladies

My senior researcher has already had his girl friend. However, a girl who is in the same club with him is also planning to make him her boy friend.
When he talked about it, he said ”I‘m a center man”
What it means is “If he were to be shared by both of the girls, left half of his body would be owned by his real sweetheart and the other half would be owned by the other,and finally borderline would be written by felt-tip pen.“

He seems to be good at grasping females‘ hearts.