How do I tell them I don't want them to go out?

It's that time of the month again for me and gee wiz have this PMS cycle been crazy. My boyfriend, the 22 year old lad with the 16 year old's relationship maturity has been hanging out with his group of new friends every day for the past week.

I have NOT been ok with this but this is a relationship so OF COURSE he can hang out with whomever he likes (of course as long as he doesn't cheat or disrespect me).

Now here is the thing, I've been bottling it up all week to the point where something very silly set me off. He wants to go sailing for the first time, without me, (I should mention I'm in another country doing research for my thesis). This group of friends are people he met a few weeks ago and he works with and I have yet to meet any of them. So I finally flipped after a week of being supportive as f*ck on him hanging out with them.

I don't want him to go sailing tonight...

He wants to go sailing tonight.

I told him I feel left out and after him ditching me for the past week (I've been asking to watch a movie at night), that I feel uncomfortable with him going out again.

He's still going.

I'm between exploding 💣 and crying a river.

That sailboat will be there alllllllllll summer.

The movie will likely be there forever.

We've been dating for four years

He has socialized with these people for a week.

Help?