Is it permissible to caress one's wife with the words "my angel" or "my houri," and is that considered an تجاوز (overstepping of bounds) against the angels and the houri of paradise?

If by saying to your wife, "my angel," you intend to liken her to angels, then this is forbidden (haram), because the implication of your statement is that there are females and males among the angels, and that there is marriage and affection between them, which is false. Therefore, you must avoid this word and replace it with another, such as "my houri."