I just read the book "Five Languages of Love." Basically, the concept is everyone speaks a different love language. The five are gifts (you feel loved when you recieve a gift), words of affirmation (you feel loved when you hear "I love you" and compliments, etc), quality time (you feel loved when your SO sets time aside to specifically be with and talk to you), acts of service (you feel loved when your SO does things for you such as clean the apartment, mow the lawn, do an errand to help you out, etc), and physical touch (you feel loved when your SO holds your hand, goes out of his way to hug or kiss you, etc). Now of course, all of these things are loving, and we can all recognize them as such, but if your boyfriend isn't showing you his love in the specific way that you need, you'll grow distant. And same with him, you probably aren't speaking his love language. For example, my boyfriend shows his love by giving me gifts. I get flowers, teddy bears, jewelry, and other very thoughtful and meaningful gifts all the time. Even just a random card every once in awhile. And I appreciate all those things and I appreciate them even more because I know that's how he shows his love. But the way I feel most loved is words of affirmation. I need him to verbally express his feelings of affection and love. His love language is physical touch (not just sex, most guys would probably assume their love language is physical touch because of sex, but this is a whole separate thing). He needs me to show my love with random hugs, kisses, touching his back when I walk by, offering massages, etc. That's all really important to him just like hearing him say "I love you" and "we'll be together forever" and such are very important to me.
If he isn't speaking your love language, then even though you know he loves you, you won't feel it, if that makes sense. And he's probably not feeling your love either even though he knows you love him.
So make the first move, make an effort to identify and then speak his love language. You said that he complains about your nagging. Whether you think you are nagging or not, that is how he is interpreting it. I don't know the situation, but I'll take a guess that he needs to have verbal affirmation to feel loved and appreciated. So when he's not getting this affirmation or when he's getting the opposite (what he's calling nagging), then he's going to push away. So take initiative in turning that around. Even though there's a bunch to nag to him about, make an effort and find as many things each day that he DOES do and verbally express your appreciation. And be specific. "Thanks for walking the dog, I appreciate it." "I was so glad you did the dishes, it meant a lot to me." "I hope you know how much I appreciate it when you do such and such, it helps me out." He may not be doing much, so you may have to look hard for things to compliment, but compliment any little thing. And of course, verbally express how much he means to you and how much you love him. I bet that once the nagging quits and he starts getting POSITIVE praise, he'll want to do more around the home to get more of it. He'll start feeling your love again.
And of course, it's important to recognize what makes you feel loved. You said you're displeased with how he's not doing anything around the home, so perhaps your love language is acts of service. Would you think "wow, he must really care about me" if he got up on his own and cleaned the living room or something? If so, tell him! Say "it's not just about having a messy apartment or not, when you do such and such chore, it shows me how much you care about me and by taking care of our home." Don't be naggy or confrontational about it, just say it. Maybe attach it at the end of one of the compliments. He may just not know how much it means to you on an emotional level for him to help out around the house. And of course, you catch more flies with honey than with vinegar. If you compliment him and thank him for every little thing he does rather than nag him to get him to do anything, he'll be more willing to help out.
Anyways, just my thoughts

My guy and I really turned our relationship around once we started recognizing what we needed from each other to feel loved. Even though we knew we always loved each other, those feelings weren't being expressed in the ways that were most meaningful to us. Once we each started feeling loved, we were more and more enthusiastic about finding the best ways to express love to each other. And at that point, just about everything is easier to work through.