Love interest nearly always weakens a mystery because it introduces a type of suspense that is antagonistic to the detective's struggle to solve the problem. It stacks the cards, and in nine cases out of ten, it eliminates at least two useful suspects. The only effective love interest is that which creates a personal hazard for the detective - but which, at the same time, you instinctively feel to be a mere episode. A really good detective never gets married.
Raymond ChandlerThe boys with their feet on the desks know that the easiest murder case in the world to break is the one somebody tried to get very cute with; the one that really bothers them is the murder somebody only thought of two minutes before he pulled it off.
Raymond ChandlerThe most durable thing in writing is style, and style is the most valuable investment a writer can make with his time. It pays off slowly, your agent will sneer at it, your publisher will misunderstand it, and it will take people you have never heard of to convince them by slow degrees that the writer who puts his individual mark on the way he writes will always pay off.
Raymond Chandler