Is acting in friendship with person x until the day you say you’re intrested in more than friendship with person x, and then, when rejected, avoiding ever speaking to person x again:
1. Normal and necessary behavior
or
2. Totally disingenuous?
or, does it depend completely on if you are the rejected or the rejector?
Botkin Creative 
#2. Or it’s social cowardice.
I vote #1, with the caveat that the lack of contact should only last as long as it takes for the person to get over the attraction.
Though I admit that answer is only to justify my past conduct.
#1 is justifiable as the rejectee, but not as the rejector. #2 is preferable, but merely an aspirational ideal.
Social cowardice? No. I vote number one…for the benefit of the rejected to cease his/her attraction and cause less stress for all involved.
I suppose we should want to be charitable either way. Whenever we risk something like that we are actually risking something, and thus we can actually loose.
When we loose in this manner, the temptation is either to suddenly dislike the other person–all their attractiveness got carried up into the friendship, and so the rejection carries backwards into the friendship–or to cover the hurt by avoiding the person.
But neither seems appropriate. Though the first is a temptation, and of course feelings of dislike will arise, it is ridiculous to assume the only reason we cared for person X was because you were interested in her. More likely we were interested in her because we cared for her and liked her. And anyway, as Christians, there should still be fellowship, which means ideally at least, close friendship. Moreover, in agreeing to not like her, and no longer desire her good we would be diminishing in charity toward her, and basing our charity on our physical attraction rather than Christ.
Likewise whenever something bad happens we don’t want to go near it. If I get a bad grade, I don’t want to look at the paper. If I got a letter (rather than a package) from a school I aplied to, I probably wouldn’t open it. And I would (at least for a while) not want to hear about the school. But again, to completely fly from the hurt is essentially to fly from Christ. We trust him when we go to her and show our interest. But he blesses us by giving us a cross. But we cease to trust Him by, like Peter, running from His cross.
I don’t know if this is too long, but the answer is that it is normal, fallen behavior.
That said, there is naturally some ackwardness “does she now despise me?” “Does she now dislike all the friendly time we had?” “Was he just being friendly to get me?” etc. and both parties should work hard to overcome this ackwardness.
It takes a seasoned captain to navigate such waters, and with two ships under weigh, calamity probable. Best to sail at distance, flying flags seen only by glass. parallel course.
A decade or two more experience and you two would laugh the whole thing off over drinks, and the bond would be a golden one lasting forever. We honor love, however inconveniently it comes.