This was a very pleasant watch with fewer aggravating plot turns than I've come to expect from Kdramas. I have a bunch of random, disconnected opinions:

*Ji Ho was a very likable main character. Actually, she was too charming and beautiful for the story, because I found it hard to believe that even a guy as damaged and stoic as Se Hee wouldn't immediately fall in love with her as soon as she moved in. As a reserved, logical guy myself who doesn't like talking too much, I can relate to Se Hee to a certain extent, but even I would totally speak up and tell Ji Ho that I loved her and wanted her to stay and not let her leave so easily. Also, it’s highly unlikely that a beautiful girl with her personality and outgoing temperament with a healthy sex drive who wasn’t raised in a fundamentalist religion or cult would have reached age 30 without having gone on a single date or kissed. Or that such a girl would only have 2 friends. It would have been much more credible if the actress was more plain or quirky looking. (Did anyone else think that something about her eyes makes her look Japanese?)

*Poor Jung Min, being mistreated by the Nam family over and over! Not only does Se Hee dump her with his dad's encouragement, his wife Ji Ho years later just uses her up and doesn't give anything back to her. So Jung Min goes out of her way to be totally generous to her ex-boyfriend's wife, offering her a job, using her company’s attorneys to file an expensive lawsuit for her, and then finding her a job at another company when she got rejected. What does she get in return for this? Absolutely nothing. After Jung Min's company helps file this scandalous lawsuit against their fellow industry colleague, isn't it obvious that her company is going to be blackballed and lose business? So she's totally going out on a limb for Ji Ho. And Ji Ho doesn't even bother to accept Jung Min's offer. I felt sorry for Jung Min.

*Bo Mi was so cute! I think she would have been a perfect match for any of the 3 main guys, Se Hee, Sang Goo, or Won Seok. I'm sorry that she came up empty at the end.

*Was Sang Goo channeling Christopher Walken? I liked him, but I would have dialed that back a little.

*I usually can't stand those typical Kdrama clingy girlfriend roles, but Ho Rang actually was a better example of this, and I found her very sympathetic. Won Seok was very sympathetic too, and I thought he did by far the best acting job out of the 3 male leads. Because both of them are so likable and realistic, it made their ending that much more of a disappointing cop out. Absolutely nothing changed for either of them, so why wouldn't they continue this endless cycle of breakup and makeup indefinitely into the future?

*I'm just as frustrated with Ji Ho's strange divorce decision in the last couple of episodes as everyone else. Why couldn't she instead do one the following much more sensible and less disruptive things?
A) Ask to have a temporary separation so she can think and decide what to do for the future. This is actually what she really ended up doing, except that she misled everyone into thinking that she wanted a permanent divorce, causing unnecessary pain and disruption to everyone around her. The separation should have just been discussed between the 2 of them and not announced to the whole world as a divorce.
B) Maybe actually communicate and talk things out like normal people. Just come out and tell Se Hee that she loves him but she wants him to come out of his shell and tell her he loves her, show more affection and emotion, and change their marriage contract so that it's based on love rather than paying the rent. He would have immediately agreed and things would have been fine after that. Also, they could have told their families that they want to have a non-traditional marriage where they opt out of those in-law duties. Problem solved.

*The editing was very strange. Scenes would end abruptly in odd places, switch to a different scene, and then come back in a way that was frustrating rather than artful or dramatic.