My [25F] boyfriend [26M] wants to take a friend [18F] on a cruise without me

We have dated for 3 years and things have been going pretty good. I’m planning to propose marriage soon and he has been very sweet and supportive of me.

Lately he’s friends with a girl around 18 years old (he has a male best friend at work and that’s his younger sister).

I didn’t mind much about him being friends with her as I feel platonic relationships with opposite genders are possible even if dating someone.

However, he said he wants to take her on a cruise in a few months as a delayed graduation gift. I wanted to come but he’s telling me it would just be the two of them.

When I said I could either go with them or he can’t do the cruise, he accused me of being paranoid and selfish saying that I can have a cruise as a honeymoon trip and that’s it.

I’m honest worried he is going to cheat on me with her during the cruise despite his assurances he won’t. What do I do to resolve this?

Netizens’ comments

There is absolutely no excuse or logical reason for him to be doing this except that he is screwing her or he will be using the cruise to get into her pants.

He is 100% going to sleep with her if he isn’t already. My money is on him already sleeping with her.

To resolve it, break up now. He is planning to cheat anyway. Let him go. If he doesn’t cheat now, he’ll do it later. He is an opportunist, preying on the young and foolish.