In the month that Bruce had been on the island, he made great strides in becoming the man he was before his unfortunate lab accident changed everything. Without having to worry about the Other Guy rearing his destructive, green head, he was able to relax, to have fun, to have sex, and be a normal part of society without the fear that he might accidentally harm someone because of an unexpected transformation. Sure, his control was much better these days than it used to be, but it still wasn't perfect. Sokovia proved that with how easily Wanda manipulated him.
He was also developing something of a solid friendship with very enticing benefits with Maria Hill. It wasn't something he ever could have guessed would happen when they first arrived, but given the lack of pressure from their connections to SHIELD and the Other Guy not being an issue, it was working pretty well. He was hesitant to refer to it as a relationship, primarily because he wasn't ready to commit to anyone in that way, but he had a genuine fondness for her that went beyond their sexual activities.
Tony's arrival changed everything. Sure, from a purely scientific standpoint, he was glad to have the man there, knew that he would be able to provide useful skills and knowledge to building their community. From a personal standpoint though, Bruce suspected his life was about to become hell. They were friends, yes, but Tony took a sadistic glee in sticking his nose where it didn't belong when it came to Bruce's personal life. The last thing he needed was Tony finding out what he and Maria had been getting up to.
When he returned to his shelter from his nightly urination before sleep, he sighed to see that Tony was there and made himself comfortable in Bruce's bed. Of course the man couldn't just ask where Bruce lived and ask if he could stay there until he got his own shelter built. That was what normal people would do.
"Tony," he said, keeping his tone mild so as not to provide the reaction that his friend was surely looking for.