How do people keep the spark alive for long periods of time in relationships, without getting bored, poisoning?

I just never stop in a relationship, and if the girl cant keep up, i usually leave them. juggling a relationship, work, friends, family, taking care of myself, and my honbies is hard work. I keep the spark by not getting sloppy n lazy, and always introduce something new, and manage the relationship some relationships have big power struggles, and the sparks are popping everywhere.