I need dating advice, pronto.?

Your NSA is officially over! It's a common situation - you enjoy a good life with a f buddy and then one of you develops stronger feelings for the other. If you care about him and his feelings in any way you would stop seeing him. If you don't care, continue it and just look out for yourself! But the fact he'd change for you shows he's really into you so if you do continue seeing him you'll really f*** him up in the long run!