My (21F) friend (22F) is ignoring that her fiancé (24M) is clearly still in love with his ex [long]

I need advice on how to approach my friend, Sarah, about her situation that's bothering me. <br><br>The issue is with Sarah’s fiancé Jim, and his obvious feelings for his ex, Lisa. I met Lisa before Sarah met Jim. They were together then. After they broke up, Jim started seeing Sarah and within a year, he proposed. Now they have a kid together. <br><br>Lisa and I used to be friends, but I haven’t seen her in years. We both started college and went in different directions. I never thought about her until Jim started talking about her again. He says he misses her, wants to hang out, or whatever. <br><br>Thing is, he’s always saying how much he loves Sarah and he wants to spend the rest of his life with her. I get that he’s still friends with Lisa, but it feels like there's more to it. <br><br>My advice would be to break up with him, but I don’t know how to tell her without ruining our friendship. <br><br>UPDATE: <br><br>I showed Sarah this post and the comments, so now she knows that I don't like her fiancé. <br><br>She told her sister everything that happened, and her sister said she was going to tell their parents because she was scared of Jim. <br><br>Their parents were not happy. They had a big fight with Jim. He said he "regretted" his past actions but that he loved Sarah and wanted to marry her. They wanted him to delete his social media until after the wedding, but he said he wouldn't do it. <br><br>The wedding is still on, but Jim asked that I not attend. Sarah said it was because I don't like him, but I think he doesn't want me there to tell her if Lisa shows up.<br><br>I don't think I'll be invited to the reception either. <br><br>I'm just waiting for the other shoe to drop and find out they broke up. <br><br>God, this is such a mess. Thank you for all the advice in my last post.