Everyone certainly has a certain criteria for choosing a partner. In some cases of anime pop culture, many "wibu" (fanatic fans of anime and Japanese culture) choose 2d characters as their partner criteria. Then they name it as "waifu".
The more widespread and up-to-date the creation of fictional creatures offered by screen culture is, it becomes an alternative way for human to choose 2d creatures as their partners, because human freedom is also to be able to choose whatever they want.