I do want to ask - are you OK with another of his partners going on a Valentines cruise with you or just agreeing because you want to be easy going? Is it an overnight trip, will you be sharing a room with him and his other partner? Either way, how will be be splitting his time with you and his other gf during the evening, and is that discussed up front? If it's not overnight, who is he going home with, and how will it feel if it's not you?
This doesn't sound like it started off very idealy, so I think some upfront communication is pretty important. Figure out ahead of time your limits for respect and time, because it seems like there's a chance your boundaries might be abused because he was not upfront ahead of time, and no matter how wonderful a person is there is still a duty to yourself to put your own wants and needs first. I hate to say he might be pretty self centered. And I take that from the 7 relationships and neglecting disclosure early on in your relationship.
Happiness will never come to those who fail to appreciate what they already have.