Doing Poorly in School Junior Year

Hey everyone, I'm a Junior in my second semester at the moment. I've locked in an AM Internship at somewhere nice last semester, and spirits are high. I decided to shift focus on my priorities a bit after accepting my SA Internship, because a lot of other facets of my life were going poorly. My health has been improving a lot and I've been going to the gym, I've been spending more time with friends, and I'm maintaining a great relationship with my family. At the moment my situation in every other regard could not be better.However, this come sat the expense of my performance in school. Last semester, I dropped from a 3.9 to a 3.7. Okay, not awful, but I was interviewing for a quarter of that time and didn't have all the time to commit to school. However, this semester, after getting through the first wave of exams, I've absolutely bombed every first wave of exams, and am already on track to getting B's this semester even if I perform extremely well going forward (around 65-80% in all of my exams).While I did study and my habits did not change, I know I'm seriously lacking that sort of engagement in my studies. I show up to all my classes and I do find the lectures interesting, but I can't find myself rallying to study the way I'm supposed to.Has anyone else experienced this? How important are good grades at this point in the game? What is the threshold for GPA and academic performance that could seriously hurt my chances? Any sort of advice helps, but school has me absolutely beat right now.