Ex-wife of a cop here. Do yourself a favor and read this book. https://www.amazon.com/Emotional-survival-law-enforcement-officers/dp/0971725403
Take it very seriously. I was given the book when my ex-husband first got out of the academy and scoffed, "That will never be us." BOY. I read it again 5 years later and it was like they were peering through our windows: His head on a swivel 24/7, him hating everyone, shutting down when he got home playing videogames and being impossible to reach. It comes from being so hyper-aware all shift long and having to decompress when off shift. The night shift was also very hard as we totally lost touch. REALLY think hard about what you want out of this relationship NOW and discuss it together. The job killed my marriage. We were together for 22 years and lasted only 8 years into his LEO career. If you stay, be very mindful of these risks and keep the lines of communication open, AND KEEP RE-READING THE BOOK.