Joan, an orphan, he says, servant in a gentleman's house where he used to visit; no people of her own, no marriage portion; he pitied her. A whisper in a panelled room raises spirits from the fens, fetches the dead: Cambridge twilights, damp seeping from the marshes and rush lights burning in a bare swept room where an act of love takes place. I could not help but marry her, Dr Cranmer says, and indeed, how can a man help marrying? His college took away his fellowship, of course, you cannot have married fellows.
— Wolf Hall by Hilary Mantel
I just can't figure this sentence out. Could you paraphrase this?