I am in an online “relationship “ with a girl but don’t know if it’s halal?

So this new Muslim whom I met online and I plan to marry but we don’t know if it would happen due to fear of my parents not accepting due to culture . We are both young (20 and 18) And would like to know if this is halal Thing to do? Is it halal to joke about (not about Islam but like teasing each other ) but also be serious and teach about Islam but plan to marry even though it’s not official or anything? Like is it Halal ?