A guy who is a interested in something serious cannot take his eyes off a girl, so there is no need to ASK: it is self-evident by the multitude of non-verbal signals an interested guy is sending.

If you have to ask, then you might as well not ask and simply not consider the guy at all - why waste time on guys who are ambivalent?

Plus, asking this kind of a question would portray the OP as desperate. I think that the general rule is not to be desperate, but if you cannot help being desperate, at least not act desperate and sort of fake it until you make it.