He loved Izayoi; this girl was his son's fiancée he shouldn't feel like a giddy teenager having his first crush. Didn't he divorce his first wife to marry Izayoi, the love of his life? Wasn't Kami supposed to have stopped him from feeling attracted to younger (and getting more and more beautiful with each one, he had to admit) women? Wasn't his first wife originally his best friend, his second (and current) wife the nanny for his children, and now Inuyasha's fiancée, Kagome?
Inutashio cursed Kami. She would never feel that way towards him, he shouldn't even try.
(That didn't stop him from being attracted to the kind and feisty girl, however.)
I don't own Inuyasha.