So he's going to have to get all the girls to like him AND all the goddesses to like him? AND everyone thinks he's a womanizing scum? (even the regular people think he's a useless otaku) Damn his job sucks, no thanks or reward at the end other then not getting his head chopped off. Apart from being able to kiss girl's and go no further (it is a shounen manga after all).
Hmm seeing as the runaway spirit guys are evil do you think they might be able to control the collar around his neck and use it to make him reveal where the goddesses are? We don't really know how the collar works so they might be able to control it and use it as a threat.
And tbh it's nearly impossible for Keima to realise anyone else likes him, he's always on the attack so he isn't too good at recognising affection towards him unless he sets it up like in the case of the swimming girl. Unless Haqua tells him or, much more likely, she gets possessed by another spirit because of the stress from not telling him and then ends up telling him when he saves her, it's not going to happen. She doesn't have a goddess after all so it's "eyes on the prize" until he's got them all.