I will say this, right here right now: That character who made you worry about such a thing is your waifu. Congratulations, you have found her. This easy, this simple, this clean. Really, this is all there's to it. However that is only a "seed" of a waifu.
Love isn't something that you obtain, is something that you create. Think of the infatuation as a seed and love as a tree, then you'll notice that, even if the seed is strong it still needs to been taken care of to become full love. Like seeds, some will take more care, some will take less and some will grow even if you don't want to.
Now, she is the seed of your waifu, depending on your actions and your will she can either become your waifu and thus your fear would be baseless because it's impossible to get bored of something you love, or not become your waifu and then you just have to try again with the next character.
To put it simple: If you can love her then love her. If you can't love her then don't do it and find someone else which you can.