Think back to One In A Million, and that disastrous dinner date at Montaldo's that Oliver couldn't seem to stop from spiraling out of control. First he self-sabotages by referring to him and Shane and "just friends." Then he struggles to say the word "date," despite seeming to have every intention of making the word leave his lips. Towards the end of dinner, he starts to get hot, removing his jacket, as if the anxiety is threatening to overtake him, becoming more vulnerable in the process. It wasn't just a lack of love, power and a sound mind that debilitated him so, it was something much deeper than that.
Perhaps the siren sound puts too fine a point on the matter. But it serves a purpose---to highlight how, like Topper, Oliver, attempting to cross the threshold of his emotional boundaries in One In A Million, had his efforts abruptly and alarmingly stifled at the point of execution. It's particularly vexing given how Shane repeatedly attempts to give him the benefit of the doubt, even going so far as to allay his fears about the other men with whom she had shared dinner at Montaldo's, and even reassuring Oliver that "[she] only dances with [him]." Even at this junction he does himself the disservice of backtracking to the idea of "more [dance] practice," an activity directly connected to the earliest---and least intimate or romantic---stages of their relationship, yet another act of emotional self-defense. Yet the question remains: why couldn't Oliver stop self-sabotaging?
It isn't until Lost Without You that the true crux and depth of Oliver's struggle is finally revealed in the little boy always trying to "protect [his parents] from the bears," his heart always broken by the women who "truly mattered" in his life. Throughout the dinner in One In A Million, it's that same little boy trying to protect adult Oliver from "the bears," sounding the alarms and warning him to stop before he got hurt again, ultimately causing him to "bomb" what could have been an incredible evening.