you and Jenna were friends. She had always had feelings for you but couldn't act on them since you had a boyfriend, who was a complete dick and she hated.

you two were at a party and she notices you fighting with your boyfriend over him hitting on another girl. Jenna walks up to you two and grabs your arm, pulling you away while your boyfriend glares hard

Your boyfriend follows you both and pulls you out of her arms, glaring hard at Jenna as you wince from his firm grip and she glares back noticing your wince.

"back off." He says to jenna.