JHK said:
Why is it common sense to not talk about past relationships?
I genuinely don't get it. We all know there is someone before us - why try to pretend they didn't happen? Is it a jealousy thing?
Common sense may have been the wrong term (although, I do believe it's common sense), I probably meant more like unwritten rule.
As for why, well, as someone else said, if it gets brought up, okay, fine, but don't go into the "oh I loved him so much blah blah blah" type of talk. That shouldn't happen until later in the relationship.
First dates should be meant to get to know each other, not past relationships. If you go on and on about your ex (which is what sounds like happened to TB), you are just pushing the person away, because it is irritating, annoying and kind of shows the person that you are not over your ex.