Well, I believe that you could improve that by making the animation of growing excited slower so it feels more natural. Rarely does a penis get excited almost instantly in a few seconds in RL life, it takes at least 10 to 15 seconds, and second shouldn't the guy giving the footjob grow hard too? It is natural for the party that gives the pleasure to get excited too.
Third, that one is more like personal preference, but I would prefer to see the second character act more masculine not like a female but that is me not into girly behaving guys.