The OP mentions experience sucking cock as a youngster.
Once again... research strongly suggests that men are, generally, bisexual, and the level to which they are bisexual is often dictated by early experience.
I am predominantly heterosexual by basic nature... but also had homosexual experiences in my youth that involved sucking cock.
As a result... even though I am only attracted to women, and only form love relationships with women, I can not help the fact that that early conditioning resulted in my having a strong desire to suck cock and to really enjoy it...
Like the OP, for a long time my fantasies would evaporate as soon as I came, and I would feel some level of shame or embarrassment about them, since I really had no interest in a serious sexual relationship with another man.
Eventually, I came to grips with the realization that my response was simply something that got programed into me at an age when my sexual imagination was in its formative stage... it affected the way my brain is wired... and really has nothing to do with my relationship preferences, or day to day actions...
I can choose to act upon those fantasies, or not.
To this day I really enjoy gay porn, as well as straight porn... I still regularly fantasize about sucking cock... but I also realize that this is just a conditioned response, and that the love and fidelity I feel for the woman in my life is what dictates my actions.
I do not worry about "what it means"... because it doesn't 'mean' anything except that I had an early experience that was pleasurable and now have that association stuck in my brain.
As a caveat... yes... you can become addicted to sucking cock... or any sexual activity that constitutes an extreme from your norm... As Anais Nin wrote, exotic flavors dull the palate to ordinary tastes.
You can get caught up in fantasies and begin to see these notions as integral to the person you are... and, given the fact that many men are profligately promiscuous, and capable of emotionally uninvolved sexual behavior, you can form a habit of casual sexual encounter that does not involve your heart and become quite used to, and even narrow your sexual response to this kind of dangerous or empty sexual conduct.
It is okay to experiment and indulge your desires, as long as you are able to discern that these desires are not really YOU, but merely the echoes of your early experience at a formative age.
For myself... I played around with it in my youth... tried it a handfull of times, both to ascertain that I really wasn't emotionally attracted to men, and to "get it out of my system"... basically, to eliminate that sense of always wondering and never having tried it...
I have those memories to draw on in moments of fantasy... and, having been there, and done that, it was easier, in subsequent years, for me to turn my back on it and dedicate myself to fidelity with one woman.