Is it better for my boyfriend to kiss my chest with his eyes open or closed?

Well, kissing the chest is a very provocative thing during sex. From the perspective of human nature, breast kissing is due to human nature (we all belong to mammals). As for whether to close your eyes, this is a matter of personal habit, but it can be said that flirting is a process of both sides. Men tease women to kiss their breasts, and women feel the flirting process, which makes men react physiologically. In general, closing your eyes is the most obvious reflection in the process of enjoyment (and it is tight, not closed), so closing your eyes is a normal and reasonable state in the eyes of most men.