Unsure about what's going on with this cap female

After the initial high of emotions comes a plateau phase where people become stable and don't feel those intense emotions but a stable feeling of connection which is good. It is good she is still msging you. Maybe give things some time to see if she occasionally msgs like before. Also she is with friends and still thinking of you and msging you which is a good sign. Also better to give things some space, intense emotions do drain people so maybe she will be normal after sometime.

Yes, she could be busy, we take self-care time seriously (nothing to worry about). Or it could be bcz you did/said something that made her doubt her happiness with you, or even worst, lost the admiration of you. It takes a lot for us to lose it, but its very likely of us to drop anyone's that crossed us in a heartbeat.

Its also possible if its bcz of something you did not say/did not do, maybe you sounded unenthusiastic/passive/boring in texts and she is now having doubts about you because she thinks you will slow her down in the future.

My advice: do not seem clingy (remember Caps are independent and desire security), its important to not directly confront her either (Caps are defensive and emotionally guarded), but find a way to let her know that you need some answers (Caps values honesty and depths), and she will happily obliged if she doesn't feel attacked. Do not pull-off unless that is something you really want, bcz thats exactly what you'll get. Caps values consistency through actions and not words.