Maybe those Sires should consider that regaining the love of their wifes is a task for a true Samurai - for when they are unable to say "I love you" - what greater goal can there be achieved than managing to do so? Battling the own fears, the own limitations and borders?

Maybe, too, that they should consider another tradition, one which I know in particular in special from the european knights of the medieval age:
Make lyrics, and poetry, for their beloved ones.

It may be even harder than those words "I love you" - but the greater the challenge, the greater the reward, and what can there be greater than the love and passion of the beloved one?

A small tip for starters:
Take a piece of paper, close your eyes and think of the 3 or 5 things that you value and admire most about your wife. And then make either a haiku from it, or any other form, be it small rhymes, a poetic play with words or what ever else your ability to polish words to shining pearls allows for.

Do fear nothing - like a knight, a samurai would not fear anything, except the failure, the breaking of the own determination.

Well, maybe, when you come home next time, you close the door, go to your lady, kneel down and take her hand and kiss each of her fingertips, and then just rest your cheek against it with closed eyes.

It is not always about words, for they can express only part of what humans feel, of what humans are and what they hope for. Try it - a smile shall be your reward, like when the sun rises over the horizon and kisses the clouds and the countryside.