Basically, I was upset because I was afraid that he had realised that he couldn't actually cope with living with me. I am pretty crappy to live with, messy, not very good at cleaning up said mess, occasionally let personal hygiene slip as well (:(), tend to retreat into myself quite often and want long periods of mumsnet time alone time. The latter isn't a problem at all because we're very well matched on that point and mostly do our own thing in the evenings, although we occasionally have to poke each other and say "Oi - shouldn't we do something together?"
The first I worry about, and we have talked about before. I can let it get bad. I'm nowhere near the level I was at when I lived alone (it was bad to the point that health visitors were doing unscheduled home visits, I had a family support worker and on one of my monthly "support" meetings with them they brought in a support social worker, who said there wasn't really much he could offer in the way of support but did give me a checklist of basic cleaning/home hygiene standards which was actually the most helpful thing that happened in all that time!) - OK, so, it's not that bad any more. But I am generally crap at sticking to things I've promised/agreed/planned to do.
I was worried because I told him ages ago, that if he was planning to propose I didn't want him to do it until after we had been living together, for the second time (ie, now/here) for a decent amount of time and he knew he was really up for it. I didn't want the resentment to build up and then it all come out one day. So, he ignored this and proposed just before Christmas (bearing in mind we moved this summer!) It took me a long time to give him an answer because I was really worried about this. We had lived together before he came over, but only for 9 months, he was working nights so we were on different time zones, I was in the absolute worst blackest period of depression I have ever been and it was shit. It did us a world of good for him to actually move out, but I was worried that maybe the living together was the problem. Not helped by him being really shocked/upset by the state of my house one time when he came home for a visit. But anyway - all of this was why he ended up living over here alone for so long. He proposed, and it turned out he hadn't ignored it at all but had taken it into very careful consideration and this was one of the things we talked about before I said yes, and one of the reasons that I did say yes even though I had felt that it would be unwise.
Since we did get engaged, I have felt so happy and settled and secure. It is such a different feeling to me, from being with someone where you don't know if you want to be with them for life or not. I felt like he had accepted me, faults and all, and he had really thought about it and he really wanted to do it. And all of this was true. But then coming here and we've ended up talking about the cleaning thing again and he is frustrated because I haven't done things I have said I will do and I started to get scared that he had "downgraded" the relationship and that maybe he was questioning whether he could actually live with me after all, and it was just my worst fear - that he'd given me this security and happiness and now he was going to take it all away because I wasn't good enough. And this time it wasn't just me, it was DS, and having given up everything back in the UK and the life here that I am really enjoying and starting to feel like I am living and coming out of the black hole I have been in.
But, yes. We talked and he said no, in no way is he questioning whether he can live with me, he was frustrated about a particular thing and not me in general and that even if me being crap (my words) is the best I can be that he wants that anyway, he is happy with that and he already made the decision ages ago that he is happy with that and that was when I was even worse 
So I have concluded I am both quite incompetent at having/being in relationships, and also that I am very lucky to have such a lovely person in my life. Sorry to ramble at you all, but I have no friends here yet who I could spill such a story to, and in fact haven't even been to a pub spilling such stories for such a long time, that in fact it has been quite cathartic, and if you're all too drunk bored to read it, it doesn't matter. :) (And in true pub fashion, I should now really go to bed, but I won't for another hour at least I expect!) 