Hi folks, FWIW, I'd go with Ellens last post as being spot on the money.
As someone who is attached to someone with BPD, I would add that sometimes being conscious of appropriate boundaries can get pretty tough.
I think that in any situation where there is a NEED for both validation and reciprocation of your feelings (i.e. I love me, you love me too don't you?) - as is usual in many love relationships particularly in the early stages - there is a potential for getting hooked into a 'stronger attachment' with a significant other.
'Treat em mean, keep em keen' is an unpleasant yet apt analogy for what can happen to the individual in this type of relationship.
And I can vouch personally for the impact that this tug of war between want I want to hear and what I actually hear does to my emotional well being - even more so when I cannot see any rational explanation for it.
Does any of this mean that I have more specific issues than anyone else? Not according to my therapist!

but seriously, I fell in love with my partner without knowing that she had BPD and the course of our relationship in the early stages followed almost the same course as every other relationship that I have had. I say almost because after my divorce I became significantly more cautious in approaching love relationships - I held off 'falling in love' for a long time. That said when I did fall in love I made a commitment to myself and to us to give the relationship 100%
I do not feel that I am any more or less attached to my BPD SO than I have been to any other individual who I have shared a love relationship with. Actually, on reflection, I'm probably less attached than I was in some of the early relationships I had during my formative years (if only I knew then what I know now!!!).
And that's my 'man on the streets' report.
Regards
Paul.