well, the past is the past. the relationship between 2 people
currently is the present. therefore, knowing about a person's past
is good, but we should always keep an open mind that the past is
still the past, we do not want to dwell in the past, but move
forward to the brighter future ahead of us.
the human mind is hard to perceive. when we hear good things about
someone's past, we tend to think that, oh that was last time, now
is different.
when we hear bad things about someone's past, we tend to think,
will he/she improve or have changed? what if he becomes worse? what
if next time he/she.... what if?... what if?...
at that point, it sets someone into this extremely defensive
mode.