My (28F) boyfriend (27M) is giving me very mixed messages. How do I address it?

We have been together for a year and a half very in love. He has moved somewhere for a job for 2 months and he said he is getting the money for us to build a future. I didn’t take it well and I needed a lot of reassurance. We went away last weekend and had the most amazing time. I noticed this week he had followed a woman on instagram and I asked him for reassurance. I have done this quite a lot but I am working on it. We argued and he said I am insecure and constantly need validation and he hasn’t given me any reason not to trust him which is true. I have an anxious attachment.

During the argument he said ‘Who knows what the future holds’ ‘I know I want you but I can’t keep arguing over things like this’. He said in his previous situations with friends or women he was quick to just leave if things got bad. 

 I said to him you clearly want to breakup with me and you’re unhappy so you may aswell just end things with me. He said he’s the happiest he's ever been and I shouldn’t give him an ultimatum. He went on a drive for an hour. He came back hugged me and we both cried and he said ‘you are too special to me to lose you like this I love you’. 

We then had a nice rest of the weekend but I can‘t shake him saying ‘he doesn’t know what he wants’. I don’t know how we can go from having such a nice weekend away to him saying this. I know I need to deal with my own insecurities but I feel like now I’m waiting around for him to end it. I don’t want to bring it up again incase it triggers everything again. 

How do I address this?