Relationship Lingo ???

Due to exposure to Hollywood films, I have been bombarded with various types of relationship phrases but until today, I have no idea what these terms actually mean. The terms that I know of are:-

Boyfriend / Girlfriend – I’m sure everyone is familiar with this

Going Steady – I believe this relates to boyfriend / girlfriend

Going Out With / Seeing Someone – Are these terms meant to be associated with dating
exclusively or are they used in casual dating instances?

Dating – I believe that this term can be used to indicate either exclusive or casual scenarios

It all seems rather complex to me, if it were up to be I’ll associate dating / going out with / seeing someone with casual dating and restrict the use of going steady / boyfriend / girlfriend to exclusive dating practices.