I agree with Ginny. I am so sorry and I know this must be SOOO hard for you, can't even imagine it actually. But some men just can't be alone. This does not mean he does not miss your mom, just his way of coping. I do hope that he found a suitable match. I also hope, in time, you can accept your dad's decision. Perhaps his running to Vegas and not inviting you is his way of softening the blow?
I'm sorry.
Karen