Relationship advice

Me and my boyfriend have been together for about 18 months. In the past ive downloaded grindr and found him on there and confronted him about it. The first time he said a girlfriend of his at work was wondering about how grindr worked. he redownloaded and showed her, i accepted that asked him to delete it and he did. We went on for a while and i had forgotten about it. Then out of the blue i decided to download grindr again to mess with guys and get pics.( i wasnt using my own pic i was more pic baiting...why i wasnt sure). Again i found him on there saying he was looking for now, friends, and networking. It said he was single. I was furiated and distraught. I confronted him again he said he was looking to see what was on there. I asked him if there had been any guys he cheated on me with. He replied no, we got in a whole two day argument. I got him to delete it again. That was about 3 months ago. My suspicions got to me and i redownloaded it again tonight. I logged back in and went to my favorites and there he was active 4 hours ago. About a little less time than when he last talked to me. ...im having a slight emotional breakdown in my head again now thinking what did i do wrong why didnt we talk about anything. One thing i know about my boyfriend is that if he has a problem with me he will tell me. Ive noticed lately that when we kiss they feel one sided like im kissing a dead fish. He says he loves me every day i tell him the same. Ill usually send him some pics of myself during the week to turn him on. Then the weekend while im working he would send me some. Lately thats been one sided too. Doesnt help he keeps calling himself a cow so i understand he doesnt really feel sexy. But i know something is strange. Im sitting in bed trying to sleep but trying to think how to talk to him and what to do. I love him but lately i dont know if he truly love me as well. Id love some advice. I dont think im going to sleep much tonight