Am I a bad girlfriend?

I've been with my boyfriend for almost 3 years... sometimes I feel like I am interested in or infatuated with other people (like at work/school etc) and might chat and flirt with them but I don't take it any further. I love my boyfriend with all of my heart but I feel lonely cause we are on completely different schedules. Is it normal to feel attracted/interested in others even if you are completely in love with someone else? I would never cheat on my boyfriend and I am happy with him.