to talk or not to talk to my bf (we have a problem)

Dear guys,
I'm asking for your help! Maybe you can give me a piece of advice or just share your thoughts on the topic.

Me and my boyfriend have been in a relationship for 3 months before he left to another country to continue his studies. It was wonderful 3 months for both of us. We share interests almost in every aspect, could talk endlessly. We were very caring for each other, never had a row and when once small misunderstanding occured we solved it lovingly straight away. He said that I'm a perfect girlfriend and friend, that my very presence makes him feel so good. He did a lot to me orginizing things and helping and caring for me as no one cared before.

He even threw hints that he wants more deep relationships (or as I understood it):
1. Told me that I will make a good wife and looked glad and proud when I said once that we are married (it was in Mongolia and it's better to say you are married when locals ask you);
2. Found a ring, played with it and than jokingly put it on my ring finger. When I jokingly replied: well now I'm married woman, he seemed to be glad;
3. Talked to me about his family and children views and mentioned once that I'm the type of girl he would like to have for long relationship;
4. On New Year's midnight kissed me after clock began to strike and said that it's tradition to kiss in a new year firstly a person you want long good relationship with.

When we parted he was almost on a verge of tears (I was positively wailing) and we promised we will meet each other in summer. That was the end of January.

After he left everyhthing has changed. He did not text me often, just once in 3-4 days. One of his first messages after parting was about how easy such charming girl can find herself a bunch of other guys. I replied that yes, I can but I need only him cos he is the best for me.

I missed him and wanted to share the moments of my life with him as I used to do so I began to write more often and ended up to initiate 80% of all conversations none of which were long and meaningful. Sometimes he drops how much he misses me and wants to be by my side and come and hug and kiss me but mostly it's me saying it. He called me last week and we talked. He said that he probably can not make it in summer cos he is engaged into some uni project which is important for his bachelor thesis. Although we had really good chat next day when I sent him a message in FB he received it but has not read it although he was online several times. And it's the forth day already and my message is still unread.

Maybe he has changed his mind or his heart chenged and he does not like me that much anymore. Then why he said that he wants to see me and took courses to study Russian so he can speak better when he comes next time (I'm from Russia). But I'm so into him still. He was caring, kind, wonderful guy and our relationship is precious to me. I want to do everything I can to try and save our relationship if it's still possible!

Guys, please, help me with advice!! I want to talk to him very sincerely about what I feel and ask if he feels the same and if he sees any future for both of us. Will it look like I'm needy or pushy? Would you like it if a girl started this kind of conversation? Or better just to give him hints that I do not like the way it goes and wait when he is ready to start this conversation himself?

I know you guys are afraid of serious conversation. I do not want to scare him off. I just want to know the truth and if he is not in this relationship I will just move on with my life.

Anyways, I appreciate every advice and your thoughts!