How To Let Go

How do you let go of the romantic feelings towards someone? There’s a guy who I really like and he was the one who kept pursuing me and took me out on a couple of dates and nothing further, but he doesn’t treat me the way I know I deserve to be treated, even by someone who sees it as a casual arrangement. He rarely answers my messages and if he does they get left on read, he’s a little hot and cold when it comes to me, I feel like he plays with my emotions because he knows I like him, and I always end up making excuses for his behavior to myself. I still want to remain friendly and cordial towards him because we do work together, but I can’t keep changing the way I feel about him everyday; some days I hate his guts for how he treats me and other days I excuse it as being shy because he likes me so much. It’s exhausting and I’m wasting my time on a guy who I know doesn’t care about me or I wouldn’t be asking advice on how to let him go.