Warning: Spoilers for Loki episode 4, "The Nexus Event."
In Loki episode 4, the God of Mischief may have fallen for Sylvie, but it's not because he loves himself, as everyone believes. In the previous episode, Loki and Sylvie spent time with each other as they were trapped on the soon-to-be-destroyed moon of Lamentis-1. At first, their relationship started out prickly–after all, two Loki variants in the same place are bound to want to establish a pecking order. However, with their death seemingly quickly approaching, they warmed up to one another. By the end of the episode, Loki seemed, if not to entirely like Sylvie, then at least respect her.
However, Loki episode 4 showed that his feelings for her actually ran far deeper than expected, with romantic feelings that took even him by surprise. Mobius, understandably still angry after Loki had escaped and violated his trust, decided to poke right at Loki's new vulnerability when he mocked the trickster's feelings for Sylvie, as well as the reason for those feelings. "You like her!," he exclaimed, before going on to twist the knife: "Two variants of the same being, especially you, forming this sick, twisted romantic relationship... What an incredible, seismic narcissist–you fell for yourself!"
The thing is, Loki didn't fall for Sylvie because he's a narcissist. In fact, he fell for her for the opposite reason: self-loathing. It's important to that the running theme of Loki has been that how things appear on the surface is not necessarily how they really are; duality is the theme around which Loki–and Loki–revolve. This is true of the TVA's Time-Keepers, who just proved to be smoke and mirrors, to the TVA agents, who are really variants. Most of all it's true of Loki himself. In the very first episode, he itted that the destruction and the villainy are all an act, a projection he felt he had to maintain. Underneath it all, Loki isn't a true narcissist; that's just the role he believes he must play. And it's true that, over time, the act of playing a narcissist has arguably fused with who he really is, to some degree, but it shouldn't be forgotten that deep down, Loki is deeply insecure. It's exactly why the only person he ever could have fallen in love with is himself–or, in this case, a version of himself.
There are two ways to read this and either could be true depending on how Loki resolves in the next two episodes. One more depressing way to read it is that Loki truly thinks he deserves to be alone. Mobius says as much, asking Loki in the time loop, "Do you really think you deserve to be alone?" to which an uncertain Loki replies, "I don't know." Far from finding pleasure in the mean pranks and villainous acts he's committed, Loki feels deep guilt and self-loathing. He's never loved anyone because he doesn't feel he deserves it. Falling in love with Sylvie, i.e. himself, is the only person he'll permit himself to fall for because he doesn't deserve anyone other than his own wretched self.
But the more hopeful read on it is that, in in Loki's case, both happen to be true simultaneously. Duality.
Loki releases new episodes Wednesdays on Disney+.