My boyfriend is slowly drifting apart

I'm currently in a long distance relationship with a guy from Vietnam. In the beginning there were lot's of talking between the two of us (we both speak Vietnamese). On average we have about 1 hour video chats and half an hour of texting everyday, but now it has gone down to 10 minute video chats and only 1 minute of texting. Sometimes he also outright ignores my texts and tells me that he's "busy", but I don't believe him.As you can see, my boyfriend hasn't been giving me that much attention like he used to and it's driving me crazy. What the hell is going on here? I hate to say it, but I strongly suspect he's cheating on me with someone else. Either that, or he's legitimately busy with his life. Ugh, I can't get this off my mind. It's bothering me so much.Yes, I understand that he has his own life to live too, but still when you're in a long distance relationship with someone, a big part of it is communication. Without this key component a relationship can never work out.Btw, something to keep in mind is that he has A LOT of gay guys on his facebook friend list which he admits to talking to some of them, but reassures me that they're "just friends". In fact, Vietnam so happens to be a country with a lot of gays, so he often has regular contact with them in his everyday life.How can I get him to pay more attention to me and put more of his time on me? I really don't want to lose him! Because the truth is, he's all I have. :/ Unless I decided to dump him and find a new boyfriend who will give me all the attention that I need, although this is only a last resort.