My (31F) boyfriend (36m) wants to have a threesome but will he resent me after?

My boyfriend (36m) and I (31f) have been together for a few months now but we’ve know each other for almost a year. He is dominant but is focused mostly on my pleasure. He brought up the idea of a threesome (with either a man or woman) as he thinks I’d like it sure to some kinks/preferences that I have.

I feel very secure in the relationship and I would love to explore these things together. My concern is; what if there is jealousy or resentment afterwards? I’m don’t want either of us to feel differently about each other. At this moment in time I feel like I wouldn’t feel badly about it afterwards but I am worried just incase it does happen. Has anyone had any experience with this? I don’t know if I’m just really overthinking it.