Mark spends time with Veronika on his own as he is attracted to her, and she prefers his company over Simon's, even though she says she may like Simon more than he likes himself.
I didn't understand What Veronica trying to say about her relation with Simon in this sentence.
She is implying that Simon is a bit of a
narcissist - self love
and she is proclaiming her great affection for Simon.
She implies that Simon does not recognize his own good qualities, and so does not like himself much. Veronika sees the good in him that Simon himself may not see, but it is not enough to overcome her preference for Mark's company.
