My 3-year LDR BF is not sure about his feelings. What should I do?

Hi guys, right now I'm filled with confusion so I really need your advice.

I have a 3-year LDR, in which we spent 1 year living together in his country and 2 years in different continents. During these 2 years, he's visited me 3 times, and 10-14 days each.

Everything has been perfect, we were sweet and supportive to each other and we became an important part of each other's life.

So, my BF is a busy guy, so normally we text to ask about each other's life, or write some emails, we sometimes call in the evening and always Skype at weekends. He didn't have a lot of time for friends and such so basically I think I was one of the very few people he talked to.

Recently he ran into a girl (an ex of his friend), he mentioned to me that he gets along well with her and also said she's quite beautiful (the thing is he never praised any woman before). So I got really uncomfortable. But he assured me that there's nothing to worry about and he only loves me.

So last week he changed his job and he's more flexible with his time, and this girl contacted him and they went out for lunch, again, he told me there is nothing to be upset with. But still I got very jealous and wrote him about how I feel and that I said I thought when he has more time, I think he would talk to me more, not to spend time with another girl.

So we had a long serious discussion about our relationship. Basically he will just move to my country if he has a decent earning, same to me. However he has been making efforts to find opportunities in my place. Me, however, has considered moving there because after all these years, I realize that he's more important. But then he said he doesn't want me to be unhappy there and doesn't want me to sacrifice, and if I go, then go for myself, not for him because that way he would be in debt to me.

Then he said he doesn't know if our relationship in the past year is based on love or just habit; that he doesn't know what we usually talk about, now that he meets new friends, socialize more, he becomes unsure. Few months ago, he booked a flight to come see me for 3 weeks, I already arranged the vacation for us here. And 3 days ago he said he wants me to give him time to think about if he loves me and he said right now he's uncomfortable with the idea of the trip.

We both know that when we are together, we are both very happy and comfortable and ourselves. But when we are in distances, we don't know if our sweet talks are just habit or it's love. Actually he is my 1st BF, so I don't really know. I know that I want to be with him, I'm happy with him and afraid to lose him. And he said he also hates to not have me in his life, but right now uncertain.

I'm sorry for writing this long, it's just that everything is welled up. I'm just sad that the moment he had more time, the 1st thing is that he feels unsure about us.

What do you guys think? Is that a sign for break up? Should I be worried about that girl I mentioned above? And how do I persuade him to still come to the trip (next 2 weeks) in case he said he doesn't want to go any more?

Thank you a lot