Also, I'd like to say that having experienced depression in varying forms close up, that life with someone with depression who does not want to help themselves is miserable.
Also, depression affects diferrent people in diferrent ways and a lot of that is down to personality and levels of emotional maturity.
Emotionally mature individuals or those able to analyse themselves and how they are feeling are more likely to seek help or try and look and what is going on.
Other individuals are more prone to burying their head in the sand.
What I am saying really is that depression is not a mystical disease that takes over your body, but it is a mental health issue that can often bring out underlying characteristics and magnify them.
Not all depressed people torn angry and abusive to their spouses, but some do. I am not going to try and give you the reasons for that, but how your fiance handles depression might be how he handles life in general.
He has to posses, depressed or not, the self management skills to get through life's ups and downs. Doubts, illnesses, periods of uncertainty without directing blame or abuse at you. If he can't do that (depressed or not) he will make a terrible husband.
We can't save anyone from themselves. We sometimes watch them behaving in ways that we think make no sense and we see them make decisions that hurt us and might even hurt them too but we don't have the power to control others.