Some of you here are bothered by Sang Yan's hovering around Wen Yifan and not keeping his distance during Sleepwalking. So here are some of the info and articles that dives more into sleepwalking:
--Sleepwalking usually isn't serious. But people who sleepwalk are at high risk for injury from things like falling down stairs, jumping out of windows, run into something, walking out the front door--
--Lifestyle and home remedies:
1. Make the environment safe. If sleepwalking has led to injuries or may do so, take precautions
2. Gently lead people who sleepwalk to bed
3. Get enough sleep
4. Have a regular, relaxing routine before bedtime
5. Put stress in its place
6. Look for a pattern
7. Stay away from alcohol--
-- Articles: For more in-depth info,
https://www.mayoclinic.org/diseases-conditions/sleepwalking/diagnosis-treatment/drc-20353511
https://my.clevelandclinic.org/health/diseases/14292-sleepwalking
https://www.google.com/search?q=is+sleepwalking+dangerous&rlz=1C1CHZN_enIN1081IN1081&oq=is+sleepwalking+dang&gs_lcrp=EgZjaHJvbWUqBwgBECEYjwIyBggAEEUYOTIHCAEQIRiPAjIHCAIQIRiPAtIBCTEyMTgzajBqMagCALACAA&sourceid=chrome&ie=UTF-8
As you can see, sleepwalking can take a rather dangerous turn sometimes if not supervised. And the only way to know about what a sleepwalker does is by being supervised by another person.
Now, if you go back and watch the sleepwalking scenes of WYF, after SY gets to know that she sleepwalks, you can see that he trying to figure out her sleepwalking patterns, like what triggers her, what time she sleepwalks, what does she do during sleepwalking, what are her thoughts during it, while also making sure she doesn't get hurt during it and also trying to lead her back to her room.
Being the man Sang Yan is, who loves her, how can he follow her advice of staying away from her and locking the door, when there is atleast a possibility of potential injury or danger. If this is happening to your friend, family or someone you cared or loved, can you truly turn blindfold to all this, even if that person said to just ignore it? Can you really ignore, knowing it can turn dangerous? To prevent any serious incident from happening and to protect her, he obviously needs to be close to her. How can people see it as him taking advantage of the situation and not as him being worried?? He didn't expect some of the things done by her (like being kissed by her and her sleeping his room) while some are seen as something she really needed (like the 2nd time she hugged pretending to sleepwalk) to which he reciprocated as a form of comfort, which of course she didn't have a problem with. When he said that what you think in the day, reflects in your sleepwalking, she didn't refute because somewhere deep in her heart she wanted them, but of course not in this way. Even though, she wants to avoid him, she is quite comfortable and feels safer with him, due to her past and present relationship with him, where he stays by her side and doesn't really invade her boundaries.
Also if you remember it, the doctor WYF went to, confirmed these facts and stated that it is better to have someone by her side while sleep walking.
Hope this answers your question of why SY hovers around WYF during sleepwalking.
Feel free to express your thoughts on this.