There's three things you should know before you watch this:
1. The producers of this series are also the people who made "Second Chance", "Coffee Melody" and "Tin Jem Jai".
If you liked those, you might like "Ai long Nhai".
2. There are a lot of scenes, where it's clear that they intended to have a product placement. There are no product placements in the whole series. Either the production company is very bad at finding a sponsor or all potential sponsors did have no interest.
3. Ai long Nhai -- อัยย์หลงไน๋ -- Ai is infatuated with Nhai. That's it. That's the story.
[As an aside, the dictionary I use also gives two other meanings for หลง, which are a) [is] lost; confused; forgotten; neglected; mentally weak; b) to lose one's way, to go astray, to get lost, to be mistaken or forget; to be absorbed; to be absent-minded -- which is Nhai's personality in a nutshell]


The series -- I hesitate to call it a drama -- suffers from these points:
1. Interesting plot ideas, which never go anywhere and unconnected scenes, with plot holes and inconsistencies.
2. Side characters who can't even be called "one-dimensional".
3. Old BL clichés, and not the good ones.
4. Low funds, static scenes.

Let's elaborate:
-- 1. The series had a really strong start. I especially loved the banter between Ai and his father. When Ai first met Nhai, I expected this story: Ai falling in love at first sight, and subsequently pursuing a clueless Nhai, in more and more ridiculous situations; to the great amusemant of ai's father and friends -- I would have loved this comedy.
I liked that it was Nhai who made the first move, and his subsequent self-exploration. He was a classic case of a gay man deep in the closet (pining after a girl he will never get, getting physical with men when drunk, insisting that another man is just a friend and some internalized homophobia -- vocally claiming that touching another man is "eew"). That also would have made a really good story, maybe finally something more LGBTQ+ than BL. And they could have made this story light-hearted and funny, if they wanted. But that was quickly discarded.
Nhai's characterization as dirty and generally being a slob could also have been something new and interesting, people could have asked Ai "Why that guy?". It was kind of important but didn't translate into his appearance. He always looked styled perfectly, and I couldn't even see that his shirt was not ironed.
Scenes were often not connected, side stories discarded. I never could tell how much time had passed. Between a scene and the next, there were inconsistencies several times. Example 1: The friend group talk about Ai and Nhai several times, whether those two are together -- but there's no continuity, the discussions are always as if the friends haven't talked about it before. Example 2: In episode seven, a hickey appears and disappears, and reappears.

There's more, but this is getting long, so on to the second point:
-- 2. The side characters. I'd complain that the female characters are there just to advance the plot for the main characters -- but the friend group is more or less the same. They stay remarkably bland, considering they have quite a bit of screentime. At the end of episode two Nhai tells us about his friends in a voiceover, but this information is never important for any of the plot.

-- 3. Clichèd BL tropes that I hate.
Top/bottom dynamics, including the use of "hubby" and "wife" -- The top is manly, sucessful, knows how to get through life, perpetually horny, while the bottom is whiny, fragile, needs help constantly, reluctant when it comes to sex. There's a review here by RemmiKay, who says "This is a CLASSIC exchange of power relationship." There's actually some textual clues for that, so it works. While I don't think this interpretation is in any way intended by the writer or the producers, it made watching the series bearable. Still, even from an exchange of power relationship I'd expect that both are shown as into the sex -- Nhai continues to look like a nervous virgin whenever things turn sexual, and it gets worse the longer the series goes on. (Even if Nhai would only be playing at being reluctant, as part of their relationship dynamic, the audience should get to see that he wants it.)
There's the stereotypical gay (maybe transgender?) friend; there must be a gay friend in a romence, right? Of course, they are flamboyant, have pink hair, but they are definitely not beautiful or attractive. And it's disheartening that Nhai goes to this friend when he's unsure about his attraction to Ai and gets "Yes, of course you are the wife" as an answer. That's not helpful and also sexist.
Too many side couples. While other Thai BL productions in 2022 seem to have learned from past mistakes, this one tries to give a male love interest to everyone in the friend group. Not only do most of them not go anywhere (the one that does, just ... does, behind the scenes), the three friends also had explicitely stated that they are straight in previous episodes. (see above, inconsistent plot)

and, finally,
-- 4. low funds. The sets, few as they are, look empty. Ai's condo is supposedly "like a labyrinth" (Nhai, somewhere in the second of third episode), but it's not, and you can see that -- the living room and the kitchen are in the same room, for example. The props in the shelves etc. are obviously placeholder props; had they filmed in one of the example rooms in an IKEA, there would have been more personality to this living space. There are no knick-knacks or anything that makes a home a home. Ai's car seems to have cost most of the money they had.
That everything, the sets, the clothes and so on is mostly in white and black, really does not help.
Scenes often just were two or more people standing and talking, which made the already slow pace wven more static. Some actors need more acting classes.


Overall, I feel that the writer had some good ideas, but shied away from anything that would have made the series more interesting, either writing a good conflict (inner or external) or more comedy. Was it too daring for him?
But even if they intended to make a slice-of-life series, they would have needed something more plotty and consistent.
It's like a teenager's first fanfiction -- they love their characters, they don't want to hurt them, they write things they wish for in their relationship. But for a product that is supposed to bring in an audience, who'll remember the story, this is just not enough.



That being said, there have been two small things that need to get an honourable mention:
* I think this is the first Thai BL in which lubrication for anal sex is mentioned, and hopefully used.
* Ai explicitely states that he is bisexual. In most BLs they don't even use the word "gay".