Arya did not ask her to fake romance. All he asked was that whether his hugging create problems in her personal life they have had a history. Not to forget he had a valid reason for it as well.
Before you say his question implies he was indeed looking for a romantic angle then that hugging and holding hands wala ques was completely logical. He wanted to be sure his closeness won't affct her relationship since even he has a friend who is insecure knowing their history. You r going to stay with your Ex under the same room...things could create problems btw the personals lives of the two.
This is something guys ask in real lyf too when they need to interact wid their frnds who are in a relationship to avoid any problems.
There are bf's/guys who are protective and don't like other guys being close to their gals even if it is in a friendly manner, whats so wrong is a guy asks a gal about this. When in real life something like this is called looking out for a friend thn why is this such an issue inside the house ?
As far as Sukku is concerned...they were gud friends nd she was clearly interested in Upen. When did Arya make any move towards her. They used to talk but alwayz maintained distance...neither did they hug nor hold hands. And thr convo also was abt general stuff ... nd if Arya wanted somethng of this sort he would have hinted something but he maintained distance