A man will call his wife mon amour as well. It’s the same as if they call one another my love. The word doesn’t become feminine because you apply it to a woman. Both would say:

Mon amour, tu as pensé à acheter du pain ?

They would only call the other one amoureux or amoureuse when talking of him/her to someone else, like in:

Paul, je te présente mon amoureuse, Marie.

or

Paul, je te présente mon amoureux, Jean.

"mon" refers to the first person (adjectif possessif) of the singular. Amour is masculine word.
Thus each person of the couple refers to the other as "mon amour".

If the noun has been feminine, each would have said "ma" like in "ma bicyclette" (my bicycle).

Edit: (see comments)

The "adjectif possessif" does not depend of the gender of the possessor but the gender and number of the object. Effectively there is an exception, when the next word begins with a vowel.

Examples:

"Ma bicyclette(f)", "Ma table(f)", "Mon animation(f)", "Mon échelle(f)"

"Mon poulet(m)", "Mon chien(m)", "Mon écureil(m)"

In your examples : amour is masculine so "mon amour" and "chérie" is feminine so "ma chérie d’amour" (Don’t forget the d'!!!)

EDIT: I won’t delete my answer because of @Gilles’ comment below.

Instead of “mon amour” you should use “mon Amour” (l’Amour avec un grand A).

In this case “Amour” represent Cupid (or an angel), so basically “mon Amour” is somewhere between “my angel” and “my love” but is a proper noun. So there is no feminine for “Amour”.

When you say “mon amoureux/amoureuse” it’s “the person I’m in love with”.

« Mon amour » c’est l’être aimé (quel que soit son sexe, quel que soit celui de qui s’exprime). « Mon amoureux », « mon amoureuse », c’est celui ou celle qui éprouve de l’amour pour moi et le manifeste (il ne va pas être utilisé dans le cas d’un amour inavoué publiquement).

Aucun des deux termes n’implique la réciprocité des sentiments : « elle n’arrive pas à se débarrasser d’un amoureux qui la poursuit de ses assiduités » peut-on dire de quelqu’un qui lui affirmerait : « elle est l’amour de ma vie et je n’arrive pas à l’oublier bien qu’elle en aime un autre. »

« Mon amour » is the loved one. « Mon amoureux », « mon amoureuse » is the one who loves and express it. For neither term, reciprocity is implied.

Amour is the word for the abstract love concept, but can also be used in the singular form to mean a beloved person (mon amour) of either gender. It is then a masculine noun.

Note that amour is a very peculiar noun in the French language. In the singular form it is masculine, and in the plural form it is feminine.

Un bel amour

but

Des amours douloureuses

You can use many common nouns as pet names. In that case, you’ll naturally use them with determinants corresponding to the grammatical gender of that noun, regardless of the sex of your beloved interlocutor. Among the classical pet names, quite a few are regularly used for both men and women : amour (m. at least in the singular, love), ange (m, angel), bébé (m., baby), cœur (m, heart), trésor (m., treasure)…

As I write this list, I realise that I do not know of a feminine pet name often used for men…

Of course, less classical pet names exist and can borrow from every grammatical category and every language. (Well, maybe not every grammatical category: I’ve never heard « quatorze » or « duquel » used as pet names, as lovely as that would be…)

A literary reference is inevitable.

Surely this is a question of euphony not gender. ‘Mon’ is used merely to avoid the unpleasant conjunction of two sounding vowels: mA Amour. In ‘La grande amour’ the redundant ‘e’ is absorbed by the subsequent ‘a’ (even though the ‘e’ is slightly sounded in ‘grande’ at the end of a sentence or if followed by a consonant… )