*Groan* A deficit is a lack or inadequacy. It usually refers to funds, but here it's placed in quotes to mean a personal inadequacy. Fiduciary refers to something held in trust (again, usually about funds). In short: his inadequacies ("deficits") are affecting the trust ("fiduciary" matters) in the marriage. A lack of trust.

Firstly - it's not a sentence. It is somebody's notes. It has missing words, missing letters, abbreviations. Reading something like that isn't going to help your English at all! But - as to the meaning: 'Hammer home' is to emphasise, stress or accentuate. Fiduciary - I had never heard of. It's a legal term. http://en.wikipedia.org/wiki/Fiduciary And a pun is a play on words. I guess it's something to do with deficits - which can be financial debts, or lackings in personal traits.