After the honeymoon period in a relationship is over, and our partner raises complaints about us, or does things we don't agree with or is somehow absent, we often start to make or draw slightly negative conclusions about them or the relationship. Typically it starts off as a thought one day, but if their actions continue to match it, we can start to think that way about the relationship or them. Negative thinking doesn't only affect you, it can kill connection, communication and passion, if the thought patterns become habitual.