Hmm well I'm a Libra Sun/Moon & Virgo Venus so I can switch it somewhat.We're stimulated off of mental energy the most and perfectionists to a degree. Not in a negative way i dont believe. Libras are cardinal signs so if he's into you more than likely he will show it. Theres also the chance that if he doesnt like you now...then theres a big change that he will later. You have to be a seeker of knowledge to keep him. He'll be weary of a long term relationship if he senses that you have little interest in actively expanding you're horizons...or it's just not in your nature to be that way. Libras are intuitive too so faking the funk to impress us is something we notice. Whether he'd be flattered by that I dont know.
I dont blame you for asking...Libras really do have a flirtatious nature even when we dont like you...we're not trying to be...we just know that will keep the peace.
So I'll say this...I dont know how you all met or how many interactions but assuming you've had enough to tell...
If he's very spot on in conversations, always saying "the right" things at the right time with little hesitation then he'll going through the motions, or really isnt taken a back by you.
If he likes you...he'll appear bashful, shy, mesmerized in a sense yet still confident (because of his cardinal sign)
and again...if you didnt sense that now his feelings could change. If he knows you like him...he'll be observing you (weighing both sides).
Hope that helped.