I've read (somewhere that i can't find) that ENFJs are notorious for polluting the emotional air, in both positive and negative ways.
We're less likely to affect people in brief situations, but you're getting the brunt of it because you live with her. It's like Gollum's cave. We hobble back into our dwelling with our "Precious" and wallow with it. In the ENFJ case, the 'precious' is our left over thoughts and emotions and the lack of facets we show toward people outside of the dwelling.
That is an interesting way of putting it, and it helps me to understand a lot better, actually. I am very close to her - we are good friends, and I think she feels safe letting go of those left over thoughts and emotions around me, probably because she knows I will not judge them.
Beyond this:
How frequently does the ENFJ overpower with negative feelings?
Have you discussed the cause of negative feelings when they are apparent?
Are you also concerned about the positive feelings?
Does the ENFJ get out and about with others a good amount?
I typically know what is causing the positive and negative feelings, and we do talk about it. Often, like you say, they are remnants of the day, leftover feeling substance that has been held in for a long time. I understand that she needs a safe space to let go of it all. She spends a lot of time with other people, and I suspect that might have something to do with it.
The thing is, it's not just the negative feelings that make me feel overwhelmed. It is positive ones too. Or just... different energy levels. Maybe I just want to feel what I am feeling. Maybe I need to be reflective. Maybe I need to mourn something a little bit. Maybe I need to cherish a certain moment or event. It's not always a big deal - I'd say a lot of the time it's fine, but just sometimes I wish I had some sort of barrier or something.
I'm really big about just addressing the issue. Are you and your roommate close? If so when you feel that negative energy ask her whats wrong. Get it out of her. It may make dealing with it easier or in the least you will know what the problem is.
Maybe if she has someone to vent to (a lot of ENFJs dont depsite how many others they help) the mood in the house will lighten.
Yes we are close, and she will often talk to me about whatever is going on in her life. Like Unkindloving was saying about the left over thoughts and emotions. I think part of the problem is that I am the person to vent to a lot of the time, because she knows I am "safe" - that I will treat what she is feeling and experiencing with kindness and unjudgemental respect...
But yeah... it's not even just the negative feelings. It is all of them.
Part of Fi is having time alone to process things, reflect on what's important in life, etc. These things give us a sense of identity and focus. So, if you never get this time, it's only natural that you'd feel like you're loosing yourself.
Tell her to back it up, and if she doesn't, try taking daily walks until you move out.
Yes this is a good suggestion. I guess I like to think of my home as the place where I can process and reflect and sort of retreat, but that is mostly because that's how I think of it, not because that's how it needs to be. Walking is a great idea, and I think also going to the park in my neighborhood now that it is beginning to get a little warmer...