According to the plot information you provided, I guess you might be talking about the book " The Sick Princess Consort Loves Beauty ". The male lead is sunny and rational, and the female lead is Ye Xiyin. The male protagonist had been sick since he was young, while the female protagonist was abandoned by her biological mother and transmigrated to another historical dynasty. The male protagonist took in the female protagonist and named her Red Lotus. I hope my guess can help you.😘