Hi,
There is a conversation between a man and a woman and after a while he says: I should probably be going
Therefore, what's the difference between the above-mentioned expression and "I should probably go" ?
The continuous tense looks at the act of going as a process with duration, with length. What he is saying with it is that 'e should 'begin the act of going'. There is a slight implicationn that he is reluctant to go, reluctant to begin the act of going.
Best wishes, Clive