reporter: and so, in april, peter and lisa found themselves back at the altar. it is my honor and delight to pronounce you, once again, husband and wife. peter, you may kiss your bride. oh. what was that day like? the most magical part of it all was that cognitively, he was with me, the entire day. and it felt like ten years ago. and he just was so enamored with the whole with me, the day, our love. and it just felt so perfect. now that you ve been married twice, does he know that you re his wife? no and he doesn t remember the ceremony. reporter: that is the brutal toll of peter s disease. but for lisa, going forward with the wedding was a rare opportunity to take a special, fleeting moment and make it everlasting. these memories that we made,
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in 2009, had a picture-perfect wedding. a memory that was supposed to last a lifetime. but three years ago, peter was diagnosed with early-onset alzheimer s disease, at the age of 53. he forgot that lisa was his wife. he started to tell me all about his wife. and he was bragging about his wife to me. so, that was helpful. but i knew that he loved his wife, me. reporter: lisa became simply his favorite caregiver. but they still had sparks. we were watching an episode of new girl. and there was a wedding. he looked at the tv, and he had this smug, little grin on his face. and he said, let s do it. and he pointed at the tv, at the couple getting married. and i said, are you asking me to marry you? and he said, yes, and nodded his head and smiled bigger.