I've been reading a lot on here and I agree with a lot of what is said. I am currently in a relationship with an ISTP and it's one of the best relationships I have personally ever been in.
There is generally no fear of disloyalty and we both trust each other very much, the relationship is very relaxed and fulfilling to both parties and he is my absolute bestfriend. I think ENFP&ISTPS make great partners because we make up for one another's weaknesses.
I never get bored of being around him and we talk a lot when generally I would tire of my boyfriends and he doesn't seem to get bored or annoyed with me either.
Even though he isn't a feeler and he's not very good at emotions, he still knows that I am and he acknowledges my values and so on. He'll express his feelings in paragraphs and in the small things and he always remembers everything I tell him.
I think people in these relationships might give up easily because there are a lot of little disagreements (mostly me feeling frustrated because it can seem like he's not interested in me at times) and a lot of people forget why they cared about the person in the first place. A lot of times it comes down to understanding one another's values, interests, and feelings. This comes down to the individuals, not the type. Sometimes it can be difficult because he's extremely logical and ENFP's tend to act on a whim, he gets easily confused which at times can frustrate me. However, there is not a single time where I looked back and thought, "I hated talking to him about this" or, "that was a really bad fight." Because it's all healthy arguments and we both are aware that we care about one another extremely. The types are oddly similar as you will read anywhere else. It's a chemistry that is very surprising considering the only thing we share is percieveing. Being a more introverted extrovert it's also fine for me to stay in and do the things he wants (which is usually just watching movies or playing videogames) and it's completely fine and totally fun.
So, when it's good it's amazing. He brings me up and makes me feel so good about myself and he's always available when I need him. He's a gentleman and he's intellectual and extremely fun to talk to. Lots of deep conversations. But, you need to watch out for disagreements, when you begin to feel angry try to think about how he's probably feeling and thinking too. Despite their cold demeanor, ISTP's have a heck of a lot of feeling and emotion just like every other human being. Try to remember that. Include them and ask them about themselves instead of constantly talking about yourself (I'll be the first to admit ENFP's talk about themselves a lot.) try to understand their point of view and have fun. The ISTP is my ultimate favorite type, I always feel extremely comfortable around them and content and I'm sure you will too.