Hi, there. First of all, sorry for your luck with the ENFP you're affectionately deeming the destroyer. We do tend to bounce around a lot, so, on behalf of my kind, I'd like to apologize. Now, that being said, I do think it is an issue of maturity. It's almost like we're programmed to seek thrill. If we want to be mature adults, many times we have to fight that urge. Boyfriend and I have been in a long distance relationship for about a year now, and it is not consistently super thrilling, but I love him and we've mutually decided to be committed to each other, so I'm in it for the long run. If you get lucky, you can find an ENFP who works hard to find thrills within the relationship she's in. For example, I try to find something new about Boyfriend every month so I can tell him how much I appreciate it. The biggest issue we have is communication: I want lots of it because I like attention and he wants not so much of it because he likes space. So, he tells me when I'm being a little too much for him to process* and I tell him when I'd really like to hear from him. I think the ENFP just has to be really aware of her tendency to seek thrill and be willing to call herself out on it.
As for seeing potential when it may or may not actually be there, I will say this: You should know that the lady ENFP in question has probably, at very least, considered you an option. We tend to do that. We consider everyone an option, and typically latch onto whomever shows us attention first. Now, this is very dangerous behavior as not every guy (and girl for that matter) is a fine, upstanding member of the community. More mature ENFPs will more carefully consider their options. I got lucky, admittedly. Boyfriend is a really good man, and he cares a lot about me, so I wasn't jumping into anything dangerous. I found him extremely intriguing, so I kept talking to him. But then I realized I was being creepy, so I kept my distance for a while, and that's when he came after me.
Know this: We find the quiet men ridiculously interesting. There may or may not be ulterior motives behind her interest in you, but she may also just be genuinely interesting in pursuing friendship with you.
ENFP-INFJ relationships can work, honest. I know two couples who are happily married! It does, as any relationship does, take an immense amount of work, a shared goal to better the relationship and an individual goal to become more and more selfless. I joined this forum so I could get a better idea of how Boyfriend's mind works. I don't know that it's helping yet, but I want to know, understand, and love him better, so I'm trying. It kind of goes back to what I was saying about finding things about him that are new and exciting so I can stay excited about our relationship.
I hope this helps. Do be careful when selecting an ENFP for yourself, we're a tricky bunch. But we're pretty worth it, I think. That might just be the ENFP talking, though.
*I would recommend being careful about approaching this, as the preponderance of ENFPs don't take criticism too well. However, we do understand that you need to communicate your issues and struggles in order for a relationship to thrive.