Husband here, my wife and I were the exact same way as you. When we first got together she had been experiencing the fun of sleeping around at college and while I'm not small by any means, I had no problem pleasing her from day one. I did eventually ask her about the guys she previously slept with and size comparison between me and them, and at first she told me that me and one other guy were the biggest she had and were about the same size. After the first dildo she bought was much bigger than me I finally asked her if he was really about the same size or bigger. She finally admitted to me he was much bigger and just didn't want to make me think less of her of get upset. I assured her it in no way bothered me that she had been fucked by a huge cock but more than she kept it from me. I had always been fascinated by the idea of seeing a pussy get stretched and violated by a huge cock well before I met her so this was like a blessing in disguise for me. I eventually one night asked her who the best sex she ever had with was and this time she was honest, it was with him, granted this is after we had been together for years and I had made her cum and squirt hundreds of times. She told me it was the best because it "was just f---king" but I'm not too naive to know his huge cock had alot to do with it, especially the fact that all she wanted from him was to just get straight f---ked. After some more prodding she admitted to me his dick in her words "made her feel so full". Again I didn't let it bother me in fact the thought of my shy conservative wife being such a slut for a dick like that was just a hot image to me. We have over the years bought more toys and she always chooses the bigger ones and yes I do the difference in hownshe acts, feels and even cums when getting stretched out. She squirts so hard and gets deep in her voice when I'm fucking her with the huge cock sleeve we have. I have no problem pleasing her still but there Is no denying that she will always cum harder on something much bigger. So in short, yes she will always think about his big cock and how it felt, but that doesn't mean that's the only route to pleasure for her. She chose to be with you and my wife chose to be with me when they know first hand there is better equipment out there. But me personally don't think of her wanting or enjoying a huge cock as a problem, just as much as I would enjoy a woman with huge boobs and is super tight. So if anything I want to celebrate it and not hold her back from liking a nice big cock fucking, and actually encourage her to get some and truly enjoy it. Her getting the most pleasure out of life however it may be is want I really want for her even if it means getting railed by a man with a massive cock every now and then.
This sounds just like my wife! She pretended I was her biggest for years (which is easy, because I'm unusually large at around 8.5x5.5 naturally - although I pump for her and get over 7 inches girth - and I was always the biggest for every woman I had before), but there was always a lingering "I'm not sure about this one" because she took my dick a bit
too easily every time - even the first time, it was zero challenge for her. That's unusual at my size.
Well, maybe two years ago, she admitted she had this one black friend with benefits in college who was bigger. And although it was like pulling teeth, she admitted that he was MUCH bigger - noticeably longer (so probably pushing 10 inches) and so much thicker it wasn't even comparable. The thing that really stuck with me about the girth was that her tiny hands can fit around my natural cock all the time except when I have my absolute best erections - but she said that her hand couldn't fit around his dick when it was
soft. So this dude's flaccid dick is thicker than my hard cock, which most women consider to be a monster itself.
I tried to tell her I wanted all the details because her pleasure turns me on and, quite frankly, it was obvious that the one time we had sex while talking about her experience with him she was SUPER turned on by it. She would nearly cum from hearing his name and "monster black cock" in the same sentence. But she holds back so much!
And now, since I've been pumping for her, I've seen how her body and her mind react to bigger sizes. It's amazing. Her preference is for an absurd size. She gets so turned on and cums so quickly when I'm fucking her with more than 8.5x6.25. Usually the best is around 6.5 inches girth, but sometimes she wants it bigger than that. We've made my favorite new sexual memories when she's been stuffed with 8.5x7+ inches and her eyes roll back uncontrollably, her screams stop because she's out of breath, and everything is clinching as she's cumming hard on my fat cock. I remember the first time I fucked her over 6.5 inches of girth, she came almost as soon as I got it fully in, and I was barely moving. It was never very difficult to make her cum, but it always took a lot of movement - she loves a good pounding. Until I hit that girth, and now it's like I just stick it in and she's on another fucking planet.
From pumping, we know he was nearly 7 inches in girth. I do get a tad thicker than him when I pump all the way to 7+. So basically, I've confirmed what I already suspected: She loved his cock and came on it repeatedly and quickly just due to the size alone. And lucky for me, I bottom out on her with 8-8.5 inches, so I can fill her up as much or more than he could...but damn, I wish I got to see her take him anyway!