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 ChandlerAlcohol is like love. The first kiss is magic, the second is intimate, the third is routine. After that you take the girl's clothes off.
Raymond ChandlerShe bent over me again. Blood began to move around in me, like a prospective tenant looking over a house.
Raymond Chandler