How to fall back in love??

So my boyfriend and I have been together for almost four years now. I'm 20 and he is 21. I absolutely love this man and we have been through complete hell and back. We've been through boot camp, airborne school (he is in the Army) and individual trainings. He is mixed and my family doesn't approve of him, so we have been through all of the issues that that brings. I've always stood up to my family because I loved him and if they truly wanted me to be happy, they would get over it. (Anyway that's not what I'm asking about) We have lost the spark and excitement. We irritate each other, we don't communicate with each other and we don't have the heated sex that we used to. I sat down with him last weekend and told him everything and how I feel, and he did too and we agreed that we wanted to stay together and just work everything out. I know that we aren't leaving each other and we are working on our problems. Any advice from anyone whose been in this situation? Thank you 😊