Guy's Behavior

Why do I have a gut feeling he likes me?

a coworker who is known for being gay I believe has a crush on me. I caught him taking glances at me. he also smiles to himself when i catch him. He's super helpful to me and even watches me to see if I need help so he can drop what he's doing to help me. My gut is screaming he likes me but I don't think he's not into girls.
Why do I have a gut feeling he likes me?
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