After the Fall and the leveling up of humanity, one of the side effect of such power that has been bestowed to humanity is the heightening of emotions.
Happiness, sadness, digest, fear, anger, love and hatred are all amplified.
And such the feeling of loneliness is also amplified.
To be feeling that kind of feeling, Loki don't think it is a pleasant feeling to experience at all.
He could endure such feelings because he came from that future.
And he had managed to control it from bursting out. Add that, he had separated himself into seven part, the burden of feeling is not that obvious on him
But Erika only witnessed the events of the future and not experienced it firsthand like he did.
That is the way, the One Eyed Oracle had intended to give her younger self a chance.
She gave it to her like that instead of merging herself inside her younger self, because she wants her younger self to forge a different path than herself.