I have a boyfriend, but a friend has been flirting with me.?

The other day, my friend kissed me, and now I'm thinking about him. He flirts with a lot of girls, but told me he actually cares about me, that he wants to be with me etc. I felt things with the kiss I haven't in years. (I've been dating my boyfriend for 5 years, and don't know what to do!!!) Is it normal that things aren't as spark-like with my boyfriend? I'm worried that my friend is just messing with my head to sleep with me… How can I tell? I don't want to leave my boyfriend because I'm worried that noone will ever care about me like he does. Am I being stupid even thinking about my friend? Please helpppp!!