Why Does My Boyfriend Talk About Marriage Only During Séx?

The babe is crying that she is tired of hearing of marriage from her guy only when he's on top her:

"My boyfriend only proposes when we are making love.... .in the heat of a passionate moment he says things like 'let's get married', 'marry me', 'when do you want to get married?' 

But once we are done, he doesn't mention it again..... and I'm too shy to bring it up. Pls what should I do?

But I think most times it is ladies who ask men all these funny questions in the heat of the moment and guys are in a "wonderful" state that time, so they say anything just to make sure the action doesn't stop.

But she says her boyfriend's own is too much. What do you think she should do?