I NEEDOPINIONS!!

Say you and your significant other each have separate FB pages. And their is a couple you know with the same. You friend the husband and Wife and so does your husband. The wife accepts your husband's but denies yours, 3 times. Is that weird?
These are general acquaintances of yours. You have known them both for years, and you see each other on occasion and are friendly. As well as having many friends in common.

This is the situation I find myself in. I do not understand why she won't accept my request but will accept Seth's. AND she won't let her husband except mine either. WTF?
The catch is this..... YEARS ago she dated Seth's Best Friend and kissed Seth during. OK...then I knew her husband before they started dating and he had asked me out once, I said no...we remained friends. This was all between 10 and 7 years ago. We have hung out and been friendly with each other numerous times since then.
So...am I just being crazy for letting this irritate me? (I'm not mad or letting it ruin my day...it just bugs me.) I have talked to Seth and he thinks I need to get over it. Now if I was in an adult relationship I would tell him that it bothered me and that I would appreciate him being MY man and either de-friending her or explaining to her husband that the situation seems odd,
But I'm not in that kind of mature relationship...I have told Seth it makes me feel uncomfortable and he just looks at me and says "Well there is nothing I can do about it so get over it."

Really I don't think there is a wrong or right here...if someone doesn't want to be my friend then I can handle that. This particular situation just rubs me wrong and I want your opinion on how you would feel.