When somebody comes into your life and you get feelings, things become complicated. You get scared, and you realize you have to let somebody in or walk away from it. When you are thinking about it, something I implore you to do is to look at your potential partner and see if they need "fixed." This is something that you really need to notice and look at before you get your heart broken.
First, let me put this disclaimer here: having a mental illness is not bad, or shameful. Everyone has potential to be loved.
When somebody comes into your life romantically, it takes time to get to know them. While getting to know that person, you start to learn about their quirks and good things. The further you get into your relationship, the more you start to see the bad. There are times you see some serious problems with that person come to light. When you see those problems, there are some things that you have to choose, especially if it's something that needs "fixing."
You need to weigh out your options. Just because somebody has issues does not mean you shouldn't be with them. You should not be with them if the issues bother you or are something that you cannot live with. It's not a matter of fixing them: it's a matter of you cannot accept them for who they are right now. If they have issues with themselves, then they need to fix it. If they want you around for that, they will openly communicate with you about it. Do not be the one that fixes them because they need to fix themselves.
There are situations where people are just genuinely going through a hard time and need somebody. There is no shame in being there for them, and it is a different situation from fixing people.
At the end of the day, you cannot change somebody from who they are into something that you want them to be. If somebody has issues, you are not in charge of resolving them for that person. Recently, I heard a song by Danielle Bradberry with this quote in it: "I am not in love with you, I am in love with your potential."