These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Ron the Death Eater: People often like to forget Lisa's good qualities and paint her as a conniving shrew that stole Matthew from Alex, ignoring the fact that Lisa had no idea Matthew was the guy Alex fancied. Considering the strong bond between them, she likely would have rejected Matthew if she had known Alex was interested.
People also demonize Matthew for dropping everything to try and find Lisa and call him an evil bastard for breaking Rebecca's heart. This is forgetting that it was made clear from the start he was unsure about even proposing to her and breaking it off with her was arguably better than trapping her in a loveless marriage. And also the fact that the two of them are both victims of Alex's meddling in the first place.
Tear Jerker: When Rebecca runs into Matthew at the airport and asks "did I do something wrong?" when you know what's coming.
The Woobie: Lisa and Rebecca. Lisa was led to believe that the love of her life cheated on her when she was planning to move in with him - when it was actually her supposed best friend keeping them apart out of jealousy. Meanwhile Rebecca is clearly in love with Matthew, oblivious that he doesn't love her and is pining for his first love. Also the three days she thought he was in China, he was actually trying to track down Lisa. Try not to feel sorry for Rebecca when she shows up at the airport all happy to see him.
Luke too. He genuinely cared for Alex, wanting to take her to dinner and went to her rehearsals and performances. Instead she just strings him along while she's actually in love with his best friend.