Speaking as a father of 3 girls here something doesn't sit right here. Just to be the over protective dad role does he want you to come for three months so that it will take longer for people to report you missing? If you have only ever spoken with this person over skype and online then really all you know about him is what he has told you. So really nothing. There are many stories out there that begin like this and end poorly. I would be very careful when going about this.

With that said, if this person lived close by would you commit to spending a month and a half with them without spending some time to get to know them in person first? I really don't think anyone would. Tell him that you would like to come out for a week at most first so you can get to know the real him along with the online him. Then just take it from there. Its a romantic thought to plunge in with both feet to find love but you need to be safe and smart about it.