How truly sad. I'm a "lapsed" Witness and have had the same experience of a Witness who really pours on the love to get you back into the fold and then when you don't respond or even if you do, the love in stops or eases up.
Even if you'd responded to this intense attention, the minute he thought you were "in" he'd had gone on to someone else.
I've seen this happen over and over again in my 36 year association with Witnesses. Bible studies are conducted, the teacher and student get very close, and then it's time to move on to another Bible study and love them into the religion too.
The student either progresses or the friendship is withheld, or if they do progress, they're given over to the congregation and told to "widen out" and get their love from all the others and get involved in "kingdom activity" namely the work of converting others, that will fill the void. In some congregations there's enough social activity and friendly individuals to take over, but in some congregations, the person often suffers from severe love withdrawals at this point and drops out...it's just not there any more for them. If it happens after baptism, they eventually either fade away, or get disfellowshipped for some behavior the WTS disapproves of.
The Witnesses who do this are totally unaware that they're acting in a cultish manner. It's been used by everyone from Jim Jones to Charles Manson to the Moonies to get people into the cult, the LOVE BOMB.
It especially works on the lonely, the depressed and the frustrated, but it works on nearly everyone who gives them any response, period, at least, for a while. Witnesses are told to look for those who are "sighing and groaning" (taken from a misapplied Bible verse) and that is who "needs the truth".