lrojas1993,
welcome to the staying board! Dealing with a pwBPD can be sometimes exhausting, infuriating but also rewarding. We respect life choices people are making.
I feel that I made some sort of discovery with my fiance that's seems crucial to the reason why he views about my virginity the way he does.
My theory was since I took his virginity from him he no longer had anything special for himself since his life was pretty much ripped away by his parents and bullies, and now he feels he has nothing and is nothing and no longer has a purpose to live because he nothing else to give. That's just what I think might be the root.
It is tempting and logical to search for complicated explanations - stop please. That sort of reasoning - looking for deep problems - may sometimes yield insights but mostly leads us to deeper into confusion. Reasons have seldom something to do with a specific symptom - it is mainly emotions whether he is aware of it or not. Now behind the emotions may well be reasons in the past but it is best for us to focus first on the near term and getting the emotions back in check.
You are his first sexual partner and he is insecure. There is also a cultural bias to cherish virginity and that is highly appealing to someone prone to black and white thinking. In addition there may be sex related confused emotions and insecurities stemming from childhood abuse - going deep down there may be risky - for the time being let's stick to confused and insecure with respect to sex.
Taking a step back - that is all perfectly normal. What is not normal is that he is not able to get a grip on it. Which is typical BPD - unable to regulate his emotions.
What can you do? Not much except for validating him which may allow him to get a perspective over time.
"Yeah, Loosing virginity can be a big deal. A lot of people think it is pretty important. It certainly is special. And then thinking back, don't think it changed me much. It is confusing."
"It can be an odd feeling to think there was another one before you.<long pause, don't fill>"
"When I was in your position (only if you were) I was also wondering that. Now looking back don't think it mattered but I get that it bothers you."
"Why do men always feel so insecure."
Some part of his emotional problems may well be caused by his past abuse. There are two basic ways dealing with it - dealing with the abuse memories - dealing with the emotional problems from the abuse. The former may or may not be too painful to do at the moment. The latter would be going into the direction of cognitive therapy, quite possibly DBT which is more skill learning based. If he is sharing his abuse story he may be approachable to seek out some guidance on how to overcome it from a professional.