Spoilers below for anyone who hasn't yet watched Loki's sixth and final episode of Season 1. Be warned!
After delivering a fifth installment that was filled with wall-to-wall easter eggs and callbacks, Loki tightened its focus once more for its dialogue-fueled Season 1 finale, which introduced Lovecraft Country star Jonathan Majors to the MCU. But before all that happened, Loki changed up Marvel Studios' traditional opening by filling it with memorable lines of dialogue from across the entire MCU, as a way of presenting an audio timeline, as it were. Then, Loki repurposed one of WandaVision's most oft-repeated lines in a way that quite cleverly foreshadowed Loki's eventual heartbreak.
The Loki finale's opening moment continued in a similar fashion, only mixing real-world dialogue from Neil Armstrong, Nelson Mandela, Maya Angelou, and more with a select few MCU lines. One was Loki's "Glorious purpose!" one was Sylvie's "Open your eyes," and in between was Vision's A+ assessment in WandaVision Episode 8:
That line was spoken during the WandaVision episode's flashback sequence within Vision and Wanda's bedroom, and while those instantly classic words were in reference to Wanda's sadness over Pietro's death, it's extremely easy to apply them to Tom Hiddleston's Loki dealing with his own losses in "For All Time. Always." But in a way that syncs Loki more to Vision instead of Wanda.
Vision's entire speech during that flashback was about how he was unfamiliar with the concept of grief, because he hadn't had anything or anyone to care about in such a way that losing them made a significant impact. Of course, the beloved synthezoid evolved to develop such complicated emotions by the time he was killed by Thanos, which shone through in Wanda's version of Vision within the Hex, making it all the more depressing when Elizabeth Olsen's tragic character had to leave it all behind.
Though made of flesh and blood and not electronic bits, Loki is 100% representative of those very same feelings that Vision spoke of. As the oft-villainous God of Mischief, Loki has lived the entirety of his life - or lives, if we're accounting for all of the variants - as a friendless and loveless loner. It was made clear that Loki's proclivity for sexual relationships was entirely for physical pleasure, and did not extend to the emotional side of his psyche, which is what made his spark with Sophia di Martino's (other Loki) Sylvie so meaningful and confusing to him. He'd never felt so strongly before about another person, and while it is indeed hilariously on-the-nose for the narcissist to be so engaged by another version of his identity, it's still the most genuine feeling he's ever had in this context.
And before Owen Wilson's Mobius came along, Loki's "best friend" would have to default to Thor out of sheer necessity, but it's not like they were known for having slumber parties and playing video games together. Granted, Loki's six-episode season didn't really give viewers nearly enough of Loki and Mobius' bonding time. Still, the actors made it convincing enough, and when Loki utters the line "Thank you, my friend," in Episode 5, there's no doubting that he means each word and every letter.
Which brings us back around to Vision's line as foreshadowing. Because in the end, Loki is back where he started in terms of having no friends and no companions, only this time he is filled with the unfamiliar sense of grief, now that he'd finally found the ability to care for others. He even got to seal his feelings for Sylvie with a kiss, as weird as that was, which made it all the more difficult for him to grasp that Sylvie viewed her revenge mission as more important than continuing their relationship. He clearly thought that his own brain's chemical balance would be enough to convince her to leave the Citadel and live their lives together.
Alas, Sylvie's long life of running from the TVA had long ago hardened her instincts and her motivations, and though she clearly did reciprocate some of Loki's feelings, killing Jonathan Majors' He Who Remains was just a little too necessary. And because Loki possibly would have stood in her way as a potential sacrifice, she ported him back to the TVA, where it was essentially impossible for him to return to her. But that wasn't even the end of Loki's grief.
As he was trying to come to terms with what just happened, both from a personal perspective and from a "the woman I love just borked everything and everyone" perspective, Loki discovered that everything else he thought he knew had also gone topsy-turvy. His attempt to spread the bad news to Mobius and Wunmi Mosaku's Hunter B-15 was met with only confusion, as it became clear in those final seconds that Sylvie's murderous act had distorted the central timeline to the point where neither Mobius nor B-15 knew who Loki was. (Which is a mysterious line of questioning in and of itself.)
So in roughly the same amount of time it probably took quasi-Kang's coffee to brew, the formerly alone-and-loving-it Loki had lost both the unexpected new love of his life and an unexpected kinship. And like both Wanda and Vision, Loki came to realize just how powerful and debilitating the feeling of grief truly is. Especially when it's combined with the knowledge that countless variants of a monstrous villain are now on the loose.
Where will Loki show up next, and will he still be emotionally corrupted, or will he follow in Sylvie's footsteps and turn those dour feelings into motivation? We'll have to wait and see what happens, as it's not clear yet what Tom Hiddleston will busy himself with next, though we do know another alt-take on the anti-anti-anti-villain is coming to the animated anthology What If...? in August. For now, though, fans can rewatch Loki in all its six-episode grief and glory on Disney+ as the 2021 Summer TV season rolls on.