i just need some advice

i had never really thought about having sex with someone else until my boyfriend brought up the idea of a 3way. unfortunately he only wants one unless another girl is involved, which i wouldn't really mind until he said he only wants it that way because he'd get too jealous? idk. anyway. i haven't stopped thinking about having sex with a separate person and the thought seems very thrilling. i don't know how to talk about this subject with him without it seeming like i want to breakup. i don't, i just kinda wanna experiment being sexually open with other people (not in a cheating, betraying the s/o way LMFAO)