Don't tease him, don't kiss him for too long, gently push his arm away, keep a distance, don't let him touch your chest too easily, at least don't let your hand have a chance to touch it ~ otherwise your boyfriend's "interest" may be out of control at the beginning, and you have to move on to the next step ... you don't want to, do you? )
In fact, in this way, your relationship will have a better chance of lasting.