They will play the passive-aggressive card. A libra, when totally pissed off, hates confronting the person he is pissed off at. They won't come up and tell you the exact reason why they are mad at you. Instead, they will give you signs and would want you to understand why they are mad at you. They won't create any kind of unnecessary drama. They will stop talking to that person and start giving weird looks to that person. He will drift him from that person for a while and would want a lot of space.