Consider this:
This is a fantastic picture. When I first saw it, I was like- wow!.
I saw Luthers picture before, and saw your picture before. Honestly, they were just normal. But, in the thread that you posted this picture, the shining smile on your face, both of you, tells the joy and happiness that you share with each other and makes both of you beautiful. It was a very spiritually uplifting thread especially for people who know more or less about how you were before you met each other.
Now, this is the exact reason why I think it is not considerate to make it your avatar. When people just want to review the thread, this picture stands out by itself, over and over again. I know its not your intention to be annoying, but the result is each time I have to draw my eye balls back from the picture. Luther is much wiser to put it behind the little camera. Real gentlemen!
Honestly, this is probably not your fault. My background plays a role too. I was born and raised in a very conservative culture where physical contacts are very rare, sometimes considered imprudent, even among the families who share strong emotional ties. My dad has never touched my mom publicly, not even hands or shoulder, as I can remember.
I now understand (or at least willing to) the western culture, but my subconscious keeps telling me hey, look at the right side of the page, these two are so intimate with each other in a singles forum!
Come back to the topic. It is your picture, it is your avatar. You have all the right to set the picture as avatar. However, I wouldnt do that myself because I see the reason why it may annoy some people. It does not offend anybody. In my opinion, it just attracts too much attention.
By the way, Im not sure if the person PMed you shares the same view with me. I just let you know my own opinion as you are asking. And, thanks for asking, I voted yes, although strictly speaking my answer is no, you dont have to because you have all the right to do whatever you want to your avatar.
I love you guys, and am "jealous" of your relationship. God bless!
(Good luck with Luther's job searching if he is still doing so.)