Answer:
Because the relationship between her and her cousins has changed a lot over the years.
Step-by-step explanation:
Although she is happy to see her cousins again, she knows that the interaction between them will not be the same and that makes her happy and anguished at the same time. The cousins were grown up adults and did not share the child complicity and the close relationship they had. Rose misses it, which distresses her, but she likes to see the men and women her cousins have become, which makes her happy.