Feelings for someone else

I'm currently in a relationship and have been with him for 3 years I love him but there are times when I wish I wasn't in a relationship anymore. The things he does are starting to annoy me and get me angry all the time. It's like the love isn't there anymore and I don't know what to do. Recently I started talking to a coworker of mine and we ended up getting along really well. ( which my bf doesn't know) We laugh and talk about random things while at work and it seems as if I've known him forever. We clicked instantly which i didn't think would happen and I'm realizing that I'm starting to have feelings for him. Talking to him is making me happy and I catch myself smiling at my phone all the time now. I don't know what to do about my situation and it's driving me crazy