Most Helpful Guy
It can be hard to find a person with a compatible personality (treating you nice included) while feeling physical attraction. Also those guys may say they'd treate you well but I bet your boyfriend did at first as well. Those guys may not treat you well after years of being together though.
It's possible you may feel bored when in a relationship where the overall energy is emotionally stable. You may find people with negative attitudes more exciting or interesting. As you get older your preferences may change though. You questioning your overall satisfaction in your current relationship could be a sign of you trying to learn and make an effort to grow out of your current situation.
Most Helpful Girl
Because what you have now is what you are use to, it's "normal" for you and being treated nice for once maybe seems alien or maybe even scares you a little because you're not use to being appreciated, look you deserve more than what you have now, you owe it to yourself.