The first card we have is the reversed Queen of Swords. This card indicates that there is a block or resistance to whatever goal you are trying to achieve. It may be that you are not ready to make friends with her or you are not sure of her intentions. Also, it can mean that you are not quite ready to commit to a meaningful relationship. The reverse queen can also mean that you are afraid to open up and show your true feelings.
The second card is the Ace of Cups. This card indicates that your relationship with Sara is well balanced and stable. This aspect of the card suggests that you have learned to open your heart and trust her. It could also indicate that both of you are ready to deepen your friendship and possibly go further.
From the reading of the two cards, it seems that you can trust Sara and that your friendship with her can become deeper and more meaningful over time. So, yes, I believe that Sara can become your trusted friend.