I liked this love triangle.

"Losing My Religion" was my favorite MerDer episode and I loved their converstation.
DEREK: "Meredith."
MEREDITH: "Leave me alone."
DEREK: "Meredith-"
MEREDITH: "Just leave me alone!"
DEREK: "I just want to make sure you're alright."
MEREDITH: "No! I'm not alright? Okay? Are you satisfied? I'm not alright. Because you have a wife, and you call me a whore, and our dog died, and now you're looking at me again. Stop looking at me."
DEREK: "I'm not looking at you. I am not looking at you."
MEREDITH: "You are looking at me. And you watch me. And Finn has plans. I like Finn. He's perfect for me, and I'm really trying here to be happy, and I feel like I can't breathe. I can't breathe with you looking at me like that, so just stop!"
DEREK: "You think I want to look at you? That I wouldn't rather be looking at my wife? I'm married. I have responsibilities. She doesn't drive me crazy. She doesn't make it impossible for me to feel normal. She doesn't make me sick to my stomach thinking about my veternarian touching her with his hands. Man, I would give anything to not be looking at you!"
DEREK: "What does this mean?"
MEREDITH: "Uh, I had panties on. Black ones. Do you see them?"
DEREK: "What does this mean?"
MEREDITH: "Fix your tie."
DEREK: "Meredith, what does this mean!?"
This proves that they're still in love with each other despite her being with Finn and him being married to Addison.