The first thing you need to know about SWHDT is that it is, hands-down, the most realistic portrayal of life and love during all stages of relationships (and past them, too) that I've come across so far in manga/manwha/webtoons. For one, the protagonists are older, have gone through many experiences and events, and have responsibilities - and this all shows. They are at the point in their lives where the people around them are starting to close off their worlds to just them and their SOs/families, and it's in this midst that they're trying to figure out what they want from life.
Doe-Hee (the female lead) having just come out of a long term relationship, and Hae-Kyung, having broken up with yet another woman, meet accidentally and decide to have dinner together. And unlike in other works, there's not really instant chemistry (though there is some) - there's awkwardness, there's stilted short talk, and they don't really know what to say until it comes to the topic of their past relationships. Finding common ground, they relive their memories and tell tales, and they decide to meet weekly in order to just have someone to talk to about this. That's it. The webtoon is a romance, yes, but it's one that focuses heavily on not just their romance but the theme of relationships (good, bad, romantic, platonic) overall. It lets both the reader and the characters come to understand relationships better.
I won't delve into the progression of Doe-Hee and Hae-Kyung's relationship, but their talks and the topics and content of them are relatable in so many ways. It's also extremely refreshing to see two people who clearly have no regrets over their past loves, who learn and cherish from the memories they made with those people, and who also reflect on their own selves, their flaws in relationships and in life, and their desire to become a better person. Unlike your typical romance protagonists, having been through their experiences make them know what truly does make or break relationships.
Honestly, though it's behind a paywall, it's worth paying for (or waiting for). SWHDT is one of those down to earth, realistic webtoons that painstakingly devotes its time not to futile drama or crazy love triangles, but to just letting the reader see how the protagonists grow and reflect. It's a gem amongst not-so-well-known works online, but you'd be (and I was) lucky to find it.