I(19f) had multiple thoughts of cheating on my partner.(20m)

So, to sum it up quickly, Ive been kind of distant with my boyfriend recently. We’ve just had a lot of misunderstanding in our relationship, but he’s changing and doing everything I need to do for him and vice versa. It’s a great balance now. Sexually, that’s a different story. I don’t consider myself hypersexual but I do like to have sex. And I loved our sex life when we first got together. We were intimate quite often and had amazing chemistry when we first got together, but after a year of being together it’s changed to once a week max. The guys at my job and guys I’m around in class flirt with me sometimes and I can’t help but think about them. And being intimate with them. One day at work, a customer asked for my phone number and I gave it to him. I never cheated though. I still feel horrible and guilty because he loves me so much, What do I do?