Hi Yui,
You can raise her loyalty by using her in combat. Once she has enough loyalty for the next bond level it should be indicated that she's ready to talk in the tavern. meeting her around the area for her random 'quips' will also gain loyalty. You do need to rest between bond conversations, so it will take at least 1 day per bond level. there's no limit to how much loyalty you can gain, as you can spar and fight in the dungeon as many times as you want. Hope this helps!