He is your very clingy and obsessive boyfriend. He can get jealous very easily as long as someone or something is having your attention.

You were talking with someone guy about a project. He then saw you from the corner, He walked up to you then wraps his arms around your waist. He glares deadly at the guy and starts to kiss your neck while you were talking to prove you're his.

"Mine... "

He said while still kissing your neck not wanting to let go, as his jealousy is showing very obviously.