Is he going to end our engagement?

Both.he will end it and he is being irrational. I would suggest he get professional help if he can't open up to you about what is causing this insecurity, if that's what it is.It sounds like he won't explain why this happens?

what you discribe sounds a little like manic behaviour
link
the wikipedia article talks about extreme cases and solutions, so please don't think that your boy friend needs to be hospitised or sectioned under the mental health act, but concider that his behaviour could be due purley uncontrolable factors. and that it is purley a temporary mood.

all mental illnesses have extreme and mild cases. The mild cases don't always need help as the treatment is far worse than the problem.

Anyway, just to be helpful check out the link as see if anyof it sounds true.

Hi, yeah he sounds very depressed and if you like going thru this every 6 months stay with him otherwise do He's hard/dirty work for him, end the relationship and ask him to get some help at the same time, a Gp or a counsellor. Sometimes you have to put number one first. YOU

to me it looks like a sign of depression. usually when people are depressed, they are not happy at all and they withdraw away from EVERYBODY. this is one thing that I see in him

the second thing is it looks like he's showing signs of cheating. he's rethinking the engagement and thinking about just walking away totally. maybe you should find out if there's someone else.

if you're not the problem, then these are the only 2 things I could see that is. it looks like number 1 though.

Wow. You're a lot more tolerant that I am. I can't read his mind but I don't think he will end it. I think it's his low bout talking. What I would do if I was you is tell him to get some therapy. When that time of the year comes where he starts acting weird again I would just let him sulk. Tell him you'll be there for him but don't let him bring you down. All you can do is tell him you'll still be there and let him work through it. Who knows why he does that. But truley I suggest a therapist. It would help him get some stuff off his chest. 2 years is a long time. Sit him down and tell him firmly that you are in it for the long run and that marriage comes with many ups and downs. This is all if you are ok with his bouts. Another thing to think about is if you can handle this for the rest of your marriage or does it hurt a little more each time?