onlymedid! That is a hard thing. It's also totally natural to feel sad and not indicative of a BP thing (BlackPup's comments are totally spot-on).
Do not feel guilty for happiness. Think of this... There are times when there is so much darkness. There are times when there is so much light. Most of the time though, it is a mixed bag. Good and bad, side by side. It is better to be able to see both without feeling the need to be blinded by one or the other. Does that make any sense?