The first time my wife and I had sex was just a couple hours after she had sex with her x-BF. He was my roommate for 2 years in school and had dated my now-wife for a year. She and I were friends long before we ever had sex; probably the reason our marriage is strong is because we did have all that extra time to form a friendship, first. Anyways, I'd lay awake some nights hearing my roommate pounding my future wife's pussy and I was so envious. Then he broke up with her, she came to me for a shoulder to cry on, and we ended up in the sack. She initially resisted, telling me she'd had sex earlier, but I was determined to get into her pussy. She relented, and it was my intro and first experience with creampies; I wasn't disappointed, and I liked it. There's absolutely no feeling quite like a pussy that has recently had a larger cock inside it, and is holding the nectar of another man inside it.
Anyways, that was almost 20 years ago and we're still going strong.