Righful jealousy?

My significant other and I went out for drinks to celebrate with some friends. A “friend” of mine was patting my S.O.‘s back a great deal. Then leaning on to shoulder. Rubbing back. Then a grab/rub of the thigh under the dinner table.

I got pretty upset but didn’t mention anything until after everyone had gone. My S.O. was very unhappy and thinks I’m overreacting. Am I?