If there is a light its probably the train coming.
The r/s with a pwBPD is intense. I think a lot of us have repressed feelings to the degree that we are a bit on the numb side. The pwBPD comes around, ignores our boundaries, does a lot of mirroring and flattering and we get hooked. They idealize us, and we idealize them. They hang on our every word and seem to really care... like unconditional love. Next thing you know we are relating to them like people do in an unconditional love relationship... .which unfortunately is parent-child... not gf/bf. The connection is deep, too deep... and it regresses us, we feel things again and even see everything like a little kid. We feel joy and hope and the world looks wonderful. If it were all reality based it would be awesome. However it isn't, and the pwBPD is disordered and the idealizing and being wonderful to us switches to being clingy (which makes no sense to us)... then to hateful. Any normal person we wouldn't take crap from, but our pwBPD... we jump through hoops to please, we take more and more from them till its really abusive even. It doesn't go back to like it was at first, as that wasn't real... it was them acting out of need, and us responding out of need.
So, can it happen with someone else. Easily with another pwBPD. Most likely not with a more mature person. The numbness is the problem, we avoid feelings and tense up and learn to not feel bad stuff. Along with not feeling bad stuff... we cease feeling good stuff. We get ego driven, and find ourselves trying to be some image of success... chasing after images of what we think will make us happy, and time passes and we become numb.
It can be fixed, very hard to do, but learn to be in the moment (mindfulness) and to fully experience feelings. Things like yoga/tai chi and exercise help, as you can learn to breathe deeply and feel again. To have a really close intimate relationship with anyone, you have to be pretty low stress ... and that isn't easy. You also have to be able to trust people to be close, and if your main super relationship was with a pwBPD... good chance you keep people at a distance to keep from getting hurt. That can all be overcome, but I found I needed to have a therapist to really work on it.
Real love takes a lot of time to build, its genuine and doesn't feel like the intense BPD r/s... it doesn't have that strong insane feeling to it.
You can be a loving person with friends and good r/s, or in a form of hell with BPD r/s... but the intensity is a

, not true love.
Good luck, it hurts discovering these truths.