Give her some time first, there’s probably a deeper reason behind how she feels. You can also try asking her why, but don’t pressure her too much because that won’t help right now. For now, just hold on to the fact that you both have mutual feelings for each other. Focus on making your relationship deeper and more meaningful.
Try to learn the things she likes and what makes her happy so she can love you even more. She will surely say “I love you” to you too in time. Just don’t rush things.