Secret Romance is available on at least TWO other sites. I cannot mention them here, but a google search will immediately point you to them.
By the way, Secret Romance is not a good drama. It's a very conventional, "painting by numbers" thing, so predictable you want to cry, and it asks you to suspend disbelief all the time because of the unrealistic things that happen.
And, although Sung Hoon is surely handsome, his acting hasn't been improving since Five Children. If anything he's worse here, because Five Children was very well written and directed, so it brought out his best. He is good in slapstick but his face cannot convey emotions at all.
The couple is indeed sweet and likeable, but this rom-com could have been made in the 1950s with no change whatsoever, and frankly we've seen dozens of series and films like that (not to mention cheap romantic novels). Yes, I am watching it, because it's pleasantly relaxing after a long day. But I crochet while watching. In "W" I could never crochet while watching, because if I skipped a line it was tragic. Here you can skip whole scenes and you know what has been going on. Well, at least it's better than that utter crap, Cinderella and the Four Knights, that we saw last summer.
I suppose "Strong woman Do Bok Sun" has spoiled us, because while it was cute and fluffy it also had innovative elements and the acting was very good too, even by a relative newcomer such as whats-his-name the handsome male lead.