I don’t agree that this person must be depressed. It’s possible
though.
Dates should have different tones. Some should be fun, while some should be somewhat serious, depending on the different topics brought up. Sometimes you want to show a sensitive side, sometimes a serious side.
Just like peoples moods. If for instance you were discussing the holocaust, and survivors, I would expect a serious discussion.
If it is always sad topics and discussions, then I agree that you should not continue if this leaves you feeling sad and uncomfortable.
If I were you, I’d try bringing up happy topics, and see if it changes the tone. If he manages to be a downer while talking about
bein hazmanim, summer camps, and his favorite singers, then
This person needs professional guidance.