I live in Spain - I have for about 6 months and have no plans to leave. I took Spanish in school growing up, but only retained the usual basics. In 6 months, I've picked up a pretty good amount, my vocabulary is decent, but my main problems are what you'd suspect after only a few months - conjugations (especially with irregular verbs) and colloquial phrases.
I've recently began seeing a girl who speaks absolutely no English. For the past 10 days or so, we've texted quite a lot every day, and met up about every other day and spoken for a few hours at a time. Until now, the extent of my Spanish was learned meeting new people, so I got very good at introducing myself and discussing the things you would with someone upon just meeting them, but this has gone way past that already, and I am in "new territory" so to speak.
I can fully grasp what she's saying, and she's nice enough to speak a bit slower and explain things I don't know, and I can construct adequate responses most of the time, but It's brutally exhausting - it takes a day or two to process new information and my brain is fried at the end of the day, especially since this has nothing to do with my job. It's incredibly rewarding and even after about a week and a half I feel my Spanish improving quite quickly.
I've always been good at learning new things, I studied math and engineering, but this is my first language rodeo. So my questions is, how many of you have learned a second language to a level of relative fluency by completely immersing yourself? Was it with a significant other, intense classes, living in another country, or combination thereof? I'm not taking any classes currently. How long will I feel completely fried and exhausted before it gets easier? Did the language barrier affect your relationship (whether with just friends or significant other)? Any tips?