Benjamin Clarke’s review published on Letterboxd:
The Horror of Companionship (or lack thereof). Rather than assault the senses with nothing but an overabundance of gore or shock value, Ari Aster has built this carnival of pagan sadism out of relationships, both intimate and communal. We don't know it at first, but Midsommar skillfully roots the eventual terror of watching a group of uncultured American tourists slowly devoured by the Swedish land and its people in the standoffish behavior of its central characters. It doesn't take a love guru to see that Dani (an absolutely brilliant Florence Pugh) and Christian (Jack Reynor) aren't doing so hot after four years, but notice how even when they travel to Sweden with Christian's band of bros, they're never really together.
Contrast that with the natural fellowship of the cult members; always in groups, playing musical melodies, dancing, and moving in unison. Sounds nice, right? Not when you've already spent time with four people whose interactions are defined by their emotional barriers. The cult's very behavior throws everyone off immediately, which primes Aster to milk every last drop of disturbing imagery that he's concocted for us, both on and off camera.
While the boys put their walls up almost voluntarily, Dani is forced to shelter a litany of fear and anger that is only made worse by a recent tragedy. But as is the case with most trauma in horror films, this trauma is the catalyst for Dani's catharsis. However, in an Ari Aster film, catharsis is never easy. For a long, long while, it is grueling, upsetting, and feels more like a knife twisting further into your gut than an outcry for all to hear and understand.
Of course there is at least some sense of relief by the final shot, but it isn't really the endgame Aster has in mind. Where Midsommar shines (quite literally, in fact) is in its acceptance of the pain one must endure from unhealthy relationships in order to confront it emerge a stronger person on the other side. The immediate horror of its premise is just as fucked up as you may have heard, brought to life by sterling photography, expert sound design, and a thrilling score. But as with the genre's best films, the real horror lies in not just the effect of pain, but also the cause, and those who cause it.