What does it signify when a girl asks for a break?

My girlfriend, who is 20 and with whom I've been for three years, has decided she wants to take a break. The past few days have been tough, but she still reaches out through texts and occasionally calls me. She explained that she needs this time apart to rediscover herself, as she feels she changed too much to align with what she thought I wanted. She quickly removed our photos and updated her Instagram bio, although she mentioned she would change it back eventually. Our pictures still remain on Facebook, though. She reassures me that this is just a temporary situation and that she envisions marrying me one day. Still, I'm left feeling confused about what actions to take and how to process my feelings. I love her deeply and recognize my mistakes, but I am committed to improving myself during this time apart. My fear is that this break might be more permanent than she's suggesting. While she continues to text regularly, her attitude seems different now. It feels as if the spark between us has faded. She claims she still loves me, yet admits she's losing feelings, and I'm not quite sure what that really signifies. What does it mean when she says she loves me but is losing those feelings?