Well it certainly doesn't reflect well on Sakura and makes her actions that follow. Hell, I'd argue that on some ways it makes Sakura look worse than Yuma, why? We all know Yuma is scum for going after a taken woman but by Sakura not denying his confession it tells him one of three things
1) I am not happy in my relationship and am willing to consider any better relationship
2) while I am in a relationship, you are such a catch that I may be willing to forgo it for you
3)I love soaking up attention and will consider your advances as long as you keep giving me attention.
Considering that she also silently reinforces a negative opinion of Shinobu, probably safe to say that Yuma thought option one, maybe perhaps two. So now all of a sudden I guess in Yuma's mind, he should just keep doing what he's doing. Again, scum, but like I mentioned in the last thread, if you cant count on your girl to shut down advances in a relationship she is probably just as bad as the guy going after her and make no mistake people will go after her, even in the future.