Hello
Haven't read all the replies, but just wanted to say that something very similar happened to me after about three-months with my now husband, and father of my two children.
The guy doesn't sound like a nasty piece of work to me. I mean, this is pretty shitty thing to do, but sounds like he is fucking confused too.
Def don't send him any shitty messages. Just stay calm and collected. Be the bigger person.
I think he is just having a panic cos it is starting to get serious. And he doesn't know what to do with his emotions!
My now husband broke up with me after a week long holiday and the day after we had gone out for dinner with my parents for my dad's birthday.
He stated "incompatability" too. And when I pushed him to be more specific he couldn't really find anything.
I stepped away for a few weeks, and just kept myself busy and my friends close. I was absolutely devastated! He messaged me a lot, and I was always kind and honest to him, and explained I was confused as I thought it was going so good.
And after a few weeks, he got in contact and said he wanted to go for dinner. We did. And we talked a lot and had such a fun time.
But I refused to go back to his house afterwards (i wasn't putting out!). And I sent him a message afterwards saying I thought we had something special, and I don't know what else he was waiting for or looking for...
The next day he was outside my door with a bunch of flowers saying he had made a massive mistake.
And now we are married with two children!
You know your gut, OP. Be the bigger person. Be true and honest and yourself. If it was meant to be, and is a true genuine connection, he will figure it out. And he will be back.
And if he doesn't, then you know you did everything you could. And I am sure your knight in shining armour is just around the corner..
Good luck!