A big sister who I loved has clearly changed since her cheerful and active sister married her husband Asuka Rin

My sister and I live with two siblings who don't have parents. My beloved sister, who I had lived with since ancient times, has married. It's a very happy thing, but the fact that the older sister I occasionally met after marriage was active and energetic was clearly different. Is this the cause not because of the man I was married to? I realized that my guess is real...