Rahab75

Yes, he was, and 17 is not underage.

Elio was not underage either.

How do you mean "secretly in love with for 20 years"? Do you mean that they kept it as secret? Because I am pretty sure it was not one-sided and that they had a love affair at least before Sasiwimol came.

This reminds me also a theatrical play in many respects - to the works of Edward Albee in particular - but I strongly disagree that it is stagey or looks like a photographed play. It is extremely and very professionally cinematic.

I know Charley's Aunt (the musical version too), but that one is a completely different, cross-dressing comedy and so far not even remotely reminds me of this one.

Goodbye Charlie is a very similar plot. A womanizing Casanova who notoriously treats his lovers badly wakes up as a glamorous woman. Vincente Minnelli made a movie version of that in 1964 with Debbie Reynolds, Tony Curtis and Pat Boone.
https://en.wikipedia.org/wiki/Goodbye_Charlie

It reminds me of George Axelrod's Goodbye Charlie, if you happen to know the stage play, but with the sex change the other way around.

Actually I have had another hunch. His panicking in that erotic scene came when he recalled his numerous sexual interactions with Nott while the public is convinced he is still virgin, and the memories of all sponsors and other moguls making sexual advances to him which he had to endure came into his mind at once. It could have been too much.

If it was just trying to get famous through BL industry he would not have had a continuous and secret love affair with Nott.

It was also stated that In went to study master degree and then PHD abroad straight after he graduated, so at the age of 21 or 22, and they have not seen each other since then. So even if the 20 years separation is exact (I am still not sure), In cannot be more than 41 or 42 now.

No, others are not saying, not stating it. They are just presuming it and wondering about it in spite of the fact that it is being said. That is the whole point of my comment.

What?

Those who are making theories whether Wang has intentionally made a plan to end up where In lives: are you listening to what you are watching?

Wang's inner monologue on his way walking up to the house:

"You're right, I lied. This here isn't the latitude of 18.8801518218 and the longitude of 19.347722166. But what harm could it do? It's not like Mom has been completely honest with me either. Who knows? Going off course for a few steps could bring a big change in your life".

He literally admits he planned this all along.

In was younger than Siam and Sasiwimiol for sure. In was about to graduate while she was actively directing stage plays and she and Siam were already married. That 20 years separation was just a random, rough estimation, it could easily be 15, 17, whatever. When In graduated (at 21 or 22), he moved abroad, so they have not talked since then. It means In is more likely to be in his early 40s, but it is not impossible he is in his late 30s only.

Not that the age gap matters to me or to anyone unprejudiced, but when Sasiwimol said they have not seen each other for 20 years that was just a rough estimation. Also if I got that correctly In was reasonably younger than Sasiwimiol and Siam, he was about to graduate when the couple was already married and they were working. So In may well be in his mid-late 30s or early 40s only.

On his way heading up to the house Wang confesses in his inner monologue that he lied to his mother about the location. It is quite clear he wanted to end up there to meet In.

She is clearly a person who tries to sweep her real struggles and inner uncertainty by brash behaviour:

The ex-husband was more than likely to be in love with In, and I guess she knows about that.

I could have given Jed a punch as well for beating up Chin just because he pushed U away. He was obviously in a bad shape.

I wanna see an Asian series where a son tells such a horrible monster dad to fuck off and die alone. He beats up both his son and his lover, neither of them fight back of course, and then their wounds are not even healed, the fucker just sends a heart in text (he is not even capable of texting I love you), and Chin smiles straight away. Wtf? Asain shows really need to get over themselves when it comes to thios shit that even the most horrible parents of the universe are forgiven . Chin should have texted him back "Rot in hell". I also hate that scheming bitches like Tisa always get away with their crimes.

I rewatched the trailer and it seems way more complex than some of the theories here.
Btw Tiew seems to change clothes quite a few times:

https://www.youtube.com/watch?v=irwAFZWiUk8

Their may well be dead, I am still not sure, but in the Buddhist religion people do not go to Heaven.