It really depends in the context in which he asks you if you have a boyfriend.
He may ask you if you have a boyfriend while making conversation with you about relationships in general.
In other words, you may have been talking to each other about relationships.
These relationships could be with friends, family, coworkers and so on.
As a result, he may naturally ask you if you have a boyfriend because the conversation is dealing with relationships in general.
It just feels like the next logical place to go in the conversation.
If he asks you if you have a boyfriend when engaged in these types of conversations about relationships in general, there is a chance that he is just making conversation and going to the next logical question.
It doesn’t mean that he is actually interested in you.
When you know that he is really interested in you is when he asks you if you have a boyfriend without any reason to.
In other words, you two weren’t talking about a relevant topic beforehand.
He just happens to bring it up out of nowhere.
This is out of the blue and not expected.
This is when you know that he is showing romantic interest.
He asks you if you have a boyfriend all of a sudden because he wants to know if you are available.
He doesn’t want to invest too much time making conversation with you and not know what your status is.
He asks you if you have a boyfriend almost immediately because he wants to know if you are available and thereby worth his time to speak to.
This is normally when you know that a guy is interested in you.
He wants to ensure that you are available before putting out the real effort in talking to you over a sustained period of time.
So this is how you need to watch for it.
If it felt like he just asked you if you have a boyfriend out of nowhere with no real context before the question was asked, he is most likely romantically interested in you.
Another reason why a guy asks if you have a boyfriend is to determine just how desirable you are to other guys.
He may be the sort that wants to gauge just how popular you are with guys.
Knowing this would make him more determined to pursue you.
He may be the kind of guy that likes that kind of competition and gets a thrill out of winning someone over.
Guys like this may enjoy the chase a lot more than truly wanting to be with the girl.
He may have a history of getting girls who were already in relationships to like him and even become unfaithful to their partners as a result.
This is a guy that is turned on by this kind of challenge.
A guy like this typically finds it difficult to stay in long-term relationships without getting bored.
He needs a challenge often.
If he were to stay in a relationship that became too familiar he would feel depressed and would want to find a new conquest.
A guy like this would be more energized about the fact that you have a boyfriend than if you didn’t.
If you had a boyfriend, you would be giving him a new project.
His challenge would be to see if he can get you to like him and want to be with him.
However, if he were to succeed in this quest, he would be the type to ultimately get bored and look for a new challenge.