一辈子都爱不完一辈子都想不完
[yī bèi zi dōu ài bù wán yī bèi zi dōu xiăng bù wán]
It expresses a sentiment like 'A lifetime isn't enough to Love or Think about everything'. It reflects endless passion and boundless thoughts or imagination. The user who selects this username likely feels that there are inexhaustible things in life, either infinite emotions or ideas, always left unfinished, never-ending.