a person that you enjoy ONLY sex with not to be confused with a fuck buddy or friend with benefits. you can be in a commited relationship with a boyfriend or girlfriend and still have a sex partner or multiple sex partners. you just enjoy variety and want to engage in sex with other partners with the permission of your significant other.
i had such great sex last night with Andy. I thought Ray was your boyfriend, what happened? Ray is still my boyfriend, Andy is just a sex partner, no friendship and no romance just good fucking. I like variety and Ray understands he does the same thing and we still love each other.