Wooyoung already fell in love with Cha from the start but Cha didn't really reciprocate this, largely because he doesn't really want to get in a relationship with an omega because the omega he used to love before cheated on him.
The turning point was Chapter 20, where Wooyoung "saved/helped" Cha from that difficult and uncomfortable situation. Where Cha was basically getting taunted and ridiculed and then Wooyoung suddenly came in all fabulous and shit and basically said how he's a high quality important omega and that only Cha deserves him. It was all uphill from there. That's where Cha started to get truly in love with Wooyoung.

Can someone tell me how they ended up together cus I forgot, I remember wooyoung trying to get cha kyung joo’s attention and stuff but that’s all I remember from before they started dating. My mind is like “wj seeking for cha kyung joo’s attention then one second later they love each other and is dating and have kids” am too lazy to read it again. (Sorry if I made no sense lmfao)