I know exactly how you feel- my BPD constantly has me on an up-down roller coaster of emotions and I lean a lot on my BF for expressing said feelings. He's my best friend, so he gets put through the ringer more than anyone else.
Between him studying at an elite university, dealing with AD/HD and trying to find a job, I feel like being in a relationship with me is a huge burden on him- I feel like I don't honestly understand why he would want to put himself through all the crap I dish out, when he could be with someone normal, if that makes sense?
Despite everything though, he keeps me as level headed as he can and I've improved so much since I've met him. I think if two people honestly love each other, then they take the time to deal with whatever obstacles come their way.
And I think we can all agree there are many obstacles lol