My boyfriend plans to come visit me in the UK next year. He is from the US so no visa required. He will be staying with me for 4 weeks in the UK. First 2 weeks, then we will travel Europe for around 3 weeks and then back to the UK for 2 weeks. The issue is, he would have just completed his long term volunteering course in the US so he won't have a job by then. Both me and his family will be supporting his stay during his time here (I have sufficient money) and he will be staying with me at my parents house. We will have all the documentation proof when the time comes. His strong ties to home includes one of his parents who is handicapped and he would never leave as he supports them and a potential job offer from the place he volunteered at. Just worried about the questions at the border as he isn't great with confrentation
From May 2019, US citizens can use the ePassport gates at UK airports to clear UK immigration. It's most likely that he simply won't speak to anyone if he goes through the gates (unless he has something to declare at customs). This is in fact what happens to most people.
He might still need to speak to someone if the gates reject his passport. For instance, if the passport chip is broken or he has an adverse immigration history (i.e. previous trouble entering the UK). In this case the usual advice applies: Answer exactly what is asked using brief answers and don't volunteer information. (If in the rare event he is taken to the back for a secondary interview, that is the time for detailed explanations.)