My kids and I are in Ontario Canada, my ex has moved to Alberta. We're all Canadian citizens.. My boyfriend is British. Thanks for any help!

I am so confused. I have been divorced for almost 3 years.. I have 2 children from that marriage. Currently we have joint custody but he has left the province and not seen the children in 4 months. I have been with my bf for 2 years and he is a uk citizen. We are planning on getting married next sum...