i married jenassa and i want to turn her into a vampire. i have done 20+ minor radiant quest for the various vampires but still Vingalmo does not offer me the quest! i have turned everyone else that he sends me to (npc in riften, winterhold and markarth) and now he tries to send me to turn the ones i have allready infected... has this happned to anyone else? am i doing something wrong? can bethesda make a quest that is actually bug free? and also is there any known way to trigger the gift quest?

Reload to a save before you completed the previous radiant quest, save before turning it in, turn it in and see what radiant quest you get, if its not the one you want..reload and repeat.

Its time consuming but its easier than going through a legion of "go here and kill this Vampire" quests.

i tried that before but couldnt seem to get that quest. but i'll do it again since i have just encountered a new vingalmo related but where the other vamps direct me to him for a quest but he has no dialog option to start it thus rendering the entire vampire side missions uncompletable... jeeez!!

I've read elsewhere on this forum that Jenassa is an NPC who does not have the option to become a Vampire if she's your wife. If I remember correctly, it's because the voice actor for her did not come back and record the extra dialogue.
It's a shame since her character would have made an awesome Vampire wife and follower.

Found the thread: http://www.gamesas.com/topic/1409756-cant-get-vingalmo-to-let-me-turn-janessa-into-a-vampire/page__fromsearch__1