In this scene of Act V, scene 3, Juliet has not time to ponder the deaths of either Romeo or Paris. As she awakens from her fake-death-slumber, Friar Laurence tells her quickly all that happened:
"I hear some noise. Lady, come from that nest
Of death, contagion, and unnatural sleep:
A greater power than we can contradict
Hath thwarted our intents. Come, come away.
Thy husband in thy bosom there lies dead;
And Paris too. Come, I'll dispose of thee
Among a sisterhood of holy nuns:"
He then flees and she's left there alone. She figures out how Romeo took his own life, and she tries to drink some poison or get it from his lips. Unable to do so, she has to quickly make a decision. She cannot live without him, and she hears officers coming. She has no time. This is the reason why she has no time to grieve for Paris. They were never involved and she did not care for him. However, I'm sure if she had time, she would feel bad that he died for her.