I think about this a lot but I just assumed it was more mid-life than hormonal. I've been with my DH for 20 years, sometimes when I get annoyed with him or with aspects of our life together, my mind will think about "what if" I'd married someone else or not gotten married. Ultimately I always conclude it's better that I did what I did, but I think about it.
Also playing this game with career, thinking about specific jobs I took or didn't take, choices I made in my specialization, etc. As you get older more and more doors are closed to you so I think it's normal to think "oh what if I'd gone into family law like I thought about doing in law school? what would my life be like now?" Again, I don't think about these things with regret really, more just speculating on how my life would be different had I made other choices.
Is that what you mean? I think it's really normal as you get older.