Husband doesn't show much love affection anymore

Me and my husband met at the beginning of 2015 from a hookup app and we really liked each other. He was a non-U.S. citizen and was Chinese. We would visit each other almost everyday because we lived close to each other. We would cuddle, kiss and everything a normal couple would do. At the time, I wouldn't let him watch porn and was upset if I caught him and was closed minded at the time. I thought it was a way of cheating. As a result (at least I think so), trying to get some action with a guy on a dating site, OkCupid by flirting as many guys as he could. I caught him, slapped him, the I left him. I went back from Philadelphia to Houston to be away from him and because that's where I'm originally from. I was also convinced that he was just using me to get a Green Card. He messaged me sometimes to say he was sorry and cried a couple times on the phone. He messaged me more after that, but I ignored him and so he stopped messaging me and tried to move on. About a year later, I stopped ignoring him because I missed him and he wanted to visit me all the way in Houston by flight. At that time, I had changed a lot and was very open minded. He visited me, and we were both sorry then we decided to live together. He bought me a plane ticket back to Philadelphia to live together. We started living our lives, I found a job and was so happy. He would cook for me, cuddle with me, kiss me all the time, surprise me sometimes with little things like cooking me something special or something he knew I liked. He was soo loving and cared so much for my well being. We agreed to marry a few months later because he would have to go back to China due to his visa expiring and because we loved each other. I would have waited if it weren't for the damn visa expiring. After we married, he continued to love me as before. He helped me get my GED and helped me get into a community college. He genuinely seemed to care about me a lot. After around December of 2016 however, I have noticed that our honeymoon was disappearing. He has been showing less and less sexual affection for me. He doesn't kiss me nearly as much, he doesn't cuddle with me nearly as much, he doesn't give me as much attention anymore, we use to have sex almost everyday. Now it’s getting to once a week give or take. He rarely let’s me touch his face anymore and if he does I can’t have my hand on his face for longer than like 20 seconds before he shrugs it off. He doesn’t let me kiss him much anymore and if he does, it’s usually just a quick smack or it’s not French kissing anymore. His excuses are usually something like, “your hands are hot”, “I want to watch my show”, “your hands are cold”, “I want to cook”, or “I want to put on lotion”. It’s almost always some excuse to get away from me touching him. He use to not ever be like that at all and in fact would be so affectionate to me. I don’t want to conclude that he is cheating. I’m trying to come up with every rational explanation for his behavior besides the most obvious and easiest conclusion: cheating. He still cooks for me everyday, he still cares for my wellbeing and wants me to have the nutrition I need and so on, but it’s just his attention to me. It’s been only about a year we’ve been together since I have moved back and he is only 30 years of age and I’m 23. He tells me his excuse for less sex is his sex drive, but he watches porn everyday which I understand everybody has needs and is nothing wrong with watching porn. So a response may be that he is stressed or something, but he doesn’t seem stressed much at all. He now has a way better job than he had before when we first met, we now have plenty of money to save, we have great health insurance, we have a car now, he gets lots of vacation time, he can work from home if he wanted, he can go to work whenever he wants but he goes in from 9 to 5. He gets plenty of benefits from his office job. He loves to play the Kinect on Xbox One and watches his TV shows which we got a 4k TV from Christmas. He was way more stressed before when we first met with his job and extremely small apartment with a tiny kitchen with no room. Had stress at work and taxes were stressful and such but still was way more affectionate. I know this is turning out to be a long book report format of a question but I want to explain as much detail as I can. He has been such a nice guy, loved me so much, cared for my well-being and wants me to be successful, but his affection for me has really worried me and seems so unusual for me. I have talked to him about it, but he just said that just because he doesn’t show me affection anymore, it doesn’t mean that he doesn’t love me. His excuse was that his sex drive is really low and his work is stressful which I can understand, but he really doesn’t show that he’s stressed. He seems so happy with his job. He says he loves it and he lives his life like a happy person. There is so much to say. He openly watches porn which he has been doing, which I have no problem with. I can look at his web history and see that he was watching porn. He never does it when I’m there though. I only see his breadcrumbs like a paper towel on the floor from his cum, his internet history, and him just telling me by me asking. Recently I’ve noticed that he downloaded an app on his iPhone called “Bing” and I see him leave it on “Private” mode as if he is hiding something. I don’t see how it could be to hide porn because he openly does it and he knows I don’t mind. I feel like he’s hiding something. I’m starting to think that he would still cheat on me. That he hasn’t changed but has just gotten better at hiding it. I don’t want to jump to conclusions or anything. I see no evidence that he has done anything but all I can do is speculate. If he continues to decline and show little to no love affection, I am going to go crazy. It’s hard to focus on my college work. I haven’t raised any expectations or anything, he genuinely has showed much less affection than he has before. I need advice and please help me. I can’t go through years of this kind of relationship. I feel like I’m just married to a best friend and not a Husband.