I remember it was a long manga, and it was two childhood friends who started dating. I remember the girl was hesitant, being all “no sex!” and stuff but eventually got hooked to it, to the point where when the guy tried a fleshlight, the girl got jealous and said she was her hole too or something
If it helps, I remember one part where the girl got mad for being cummed inside while it’s not a safe day, and she said she’ll forgive the guy if she gets some parfait or something