I love you Kate?

This is a cute movie that I have a lot of fond memories watching when I was a kid.
But watching it again as an adult (it's free on YouTube by the way) I noticed there's parts that are really silly.
One is that Bill meets Kate and knows her for only two days and he says to her "I love you Kate"
Wow! That's fast. You already LOVE her? Seems a bit strong.
And even more unbelievable is that Bill tells his daughter to take Kate into her home and be her new mother!? And he asks her to do this before she's even met Kate. That's a huge "favor" to ask of someone...
It's all ridiculous and frankly, it's just lazy storytelling. A quick way to tie up all loose ends within the last 5 minutes of the film.