Rabbi Hiyya says (Yevamot 63a-b) that one should even thank a problematic wife for saving him from sin. Hakarat tov is a fundamental good midda. Even dogs are grateful.
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Who says that the reason for loving a ger is because we were gerim in Egypt? That is only a reason to make us sensitive to how they feel (I would extend this to making deprecating comments about other ethnic and religious groups). Rav Kook says that we should love all of Creation as an extension of loving HaShem.
One must, though, define the meaning of ahava. There is a famous Mussar saying that asks why a person says that he loves fish. If he loves fish why does he kill them? He actually loves his tastebuds and stomach. The Hebrew word “ahava” is related to the Aramaic word “hav” (give). One is certainly required to give to one’s wife. One signed on it before the chuppa. This also explains how one can, as Rav Kook says, love resha’im while hating their sins. One gives to them by bringing them to do teshuva (see Berachot 10a). In a way, even capital punishment is a form of love as it enables atonement.