Richard matheson- somewhere in time

Finally found the book in the library. It bears some similarity to What Dreams May Come in the sense that the "forewords" of both books were written by the lead characters' brothers. In what dreams may come, Chris' brother received a stack of transcriptions from a psychic, whom Chris had contacted from the afterlife. In somewhere in time, Richard's brother found his diary after Richard had died from brain tumor. I wonder what gives. I think this is a much better read than what dreams may come although it seems a little far-fetched. How is it possible to fall in love with a man, especially in the 1900s, within a day or two?kinda makes you wonder whether it had all been richard's imagination. Nonetheless, I still quite enjoyed the book and the movie.