Well, I really don't see anything wrong with the old guy wanting to marry at 65. I'm mean, he'd want to end his life living with someone rather than living alone. But then when he was ready to marry the 38 year old women, that was just a tiny bit scary. If the women was around his age a little, than it'd be understandable.
As for Isha accepting her father's girlfriend, I guess it'll take time.She's probably just not ready to accept how her father is ready to be with someone else rather than her mother.