I'm Dr. Jackie, an interpersonal communication researcher/professor and relationship expert. And I'm so sorry you are going through this.
As you know because you already stated this, the possibilities are probably
not positive. The first possibility as you already alluded to is that he for whatever reason (too close and got scared, too close and got confused, too afraid of hurting you and so he lied) decided he wanted to end the relationship. Instead of being a decent person by telling you in person, he took the cowardly way out.
Secondly, he may have run into an old flame at the night club who made him feel confused, perhaps at least about getting so serious so quickly. So with or without alcohol and the presence perhaps of an old friend or flame, he decided impulsively to end it.
Thirdly, and piggybacking on the previous paragraph, and I'm hoping this is not the case, but if he DID meet someone whom he used to see, he got the cold feet regarding your growing relationship and wanted to seize the moment with this former dating partner so he had to break it off with you so as to avoid guilt if he did have a physical relationship that very night. Again, I hope this was not the case since people usually break up for a reason; it would be shame if he gave up a promising relationship for a one-night stand...whether it was with someone he used to date or someone he met for the first time who came on to him and he was extremely attracted to her. I guess the possibility of having a one-night stand with someone knew would be yet a fourth possibility.
I was also just thinking that he may have blocked your texts also right after he sent you a text. I've seen that happen with clients already. And at least with my clients, it's the man who is too cowardly to break up face-to-face so the man has done it via Facebook and via texts.
Here's a fifth possiblity that I am unsure if you have considered or not.
I know you said you were dating for 3 months and that you were exclusive. I believe you that you were exclusive. However, since you travel a lot and since he allegedly also travels, can you really be sure you were exclusive? I'm not suggesting he is married. But he could be a player. I'm sure you know that "40" seems to be the magic number that people (and more often men) tend to have or start to have that mid-life crisis. So while he has been TELLING you he's only "seeing" you, you really can't be sure that during you times away that he was not also seeing one other woman or even more than one. And as unbelievable as it may sound, some men whom I liken to sociopaths who are extremely good deceivers, he may have said all the right things and behaved all the right ways--all the while he was juggling 2 or 3 or God help him even more women simultaneously.
One last possibility kind of hinges on the first possibility I mentioned--maybe he cannot move forward from a previous relationship. Maybe he thought he could and has been trying to but has been in turmoil missing her so much. Maybe at the night club he was talking to a good friend and pouring out his heart and didn't want to lead you on any longer, which could account for such an "out-of-the-blue" and late-night text.
What do you think? Do any of these things fit? Do you want to chat? I'll send you my contact info (phone and SKYPE--I do not think there are international charges for SKYPE but I'm not positive) just in case.
Please let me know. I'm on and off tonight (I'm East Coast Time in the U.S.--it's going on 6 p.m.) but will try to respond as soon as I can.
Take good care,