Hi Hols,
Welcome to the BPD Family

Not initially seeing BPD behaviors is very common, folks with BPD can often maintain a normal appearance but with those closest to them they will show their more dysfunctional behaviors.
Have you read about BPD? I found that really helpful in trying to understand what was going on with my Partner's ex-wife. A couple of books I liked about BPD are...
Stop Walking on Eggshells: Taking Your Life Back When Someone You Care About Has Borderline Personality Disorder by Paul Mason MS, Randi Kreger
and
Overcoming Borderline Personality Disorder: A Family Guide for Healing and Change by Valerie Porr, M.A.
What kinds of behaviors have you been experiencing?
I'm glad you've joined us there is a lot of support from the members here, and the site has information and tools that can help.
I look forward to hearing more of your story.
Panda39