FINAL PICK
1: Seongwoo starts dating the girl ( or is engaged to) and Daniel adopts Little Woojin and takes care of him with Big Woojin. Big Woojin has accepted the fact that Daniel doesn't have feelings for him, but still stands by him. Seongwoo meets them by coincidence, and his feelings for Daniel are rekindled.
2: Big Woojin and Daniel are getting married, and invites Seongwoo and his girlfriend. Seongwoo sees how happy they are, and gets bitter.
But Woojin deserves Daniel, and seongwoo accepts that fact.
3: Seongwoo is now working in an idol training company as a dance instructor ( he took up dance because he remembered that Daniel had loved dancing) and his girlfriend is also a dance trainer. One day he bumps into Daniel and realises that Daniel is the new dance instructor that just joined dthe company.
Choose before October !!