[34f] [37m] Not happy with bf's past - how do I deal with this?

We've been together for a year and lived together for most of that. He is very sweet, generous, affectionate, funny, good looking and ambitious. He has a great job in finance and has always been happy to provide for us both. He's the best thing that ever happened to me and treats me like a queen. He gets on really well with my family & friends and vice versa... his friends are amazing. We knew early on with each other and it's all felt very natural. He doesn't have that much of a past... He had one relationship when he was in his early 20s, it was on & off and there could never have been a future due to cultural differences so he always knew it wouldn't last, it was never serious. Then he went on 5 or so dates with a girl when he was late 20s, but decided he didn't like her enough to pursue anything further. I'm his first 'serious' relationship and the first girl he's taken home to meet his mother, and to have met most of his friends. He'd also never been on holiday with a girl before me, and I suppose we've shared many other firsts. He'd done sexual things with girls in his past but I'm the first he's had PIV sex with. We often talk marriage, kids and know it's heading that way for us.

He quit his last job (of 10 years) last June/ July; he wanted a break... he then went off to Ibiza. He's been to Ibiza a couple of times, and I came across some of his whatsapp messages 1 month before we met...It was the second time he'd done drugs, and he was drinking as well. Whilst he was there he messaged his friends about 6 Aussie girls him and his friend went skinny dipping with at 6am after a heavy night. He said he wanted to find one of them as he 'fell in love' with her. He said this to multiple people, and he was hoping that his friend had gotten one of their numbers so he could get in touch with her. He knew her name, occupation (which was actually wrong), and location (which is far from where we live). He also said she was very intelligent and sarcastic, and perhaps taller than him; my bf is 6 ft. That very evening he'd gone out with friends and some locals, and tried to share his drugs out... he likes meeting new people. When he got back home his messages were mainly about how fun the trip was, how he wanted to plan the next one, and his desire to get his head down with work.. there was no further mention of the girl. It is possible that he just wanted to see her whilst he was out there, and have a bit of fun. It's possible he was on MDMA and coke the skinny dipping night/ morning, and for much of the trip. It doesn't sound like anything happened between him and the girl, but it bugs me that he felt strong feelings for her especially as they got naked. My bf is pretty nerdy in a lot of ways, and he'd be awkward at times when he was courting me but tried to overcompensate by blurting things out. I found this endearing but he likes to be the big I am, and it's possible that his version of events aren't accurate. He claims he 'fell in love, girl was super keen. Talked her out of it. FFS. Will defo find her'. But then I also think that if there was anything there surely numbers would've been exchanged.

The annoying thing is that when he told one of the group he was seeing me one day (one of our earlier dates) the guy said: 'Lady? Is this the skinny dipping Aussie from Ibiza?' My bf put:' No brother. She was lovely but one of those you leave in a time and place. I do actually like this one'. He's told me he's never been so sure like this in the past, that during his past encounters he never really thought ahead (which makes sense as I am the first girl he's had penetrative sex with). He's always felt that we were meant for each other, especially as we've had sliding doors moments in the past. It's possible he just wanted a bit of fun with her, but then he's never seemed like that kind of guy and it seems like more from the messages.

I know he adores me and he shows me this every day - he touches me all the time (strokes, cuddles etc), looks out for me and would genuinely do anything for me. He's also amazing with kids and would make the best father. I'm trying to work out if this is really a big deal. It's funny because looks wise people have always told him he's punching, however I've always been insanely attracted to him. Even my family did not think he was my type, but I do feel I fell in love with his personality and his looks grew on me even more. He was actually pretty awkward at times when we first met, although I also found him very charming. I could tell he didn't have an awful lot of experience and would blurt things out to try and over compensate.

He really wants me to go to Ibiza with him and them all next year. I was up for it but obviously feel a bit weird about it all now. I'm not sure if I'm being unreasonable, but I would find this a lot easier to take if it'd been 5 years ago, not whilst he was in his mid 30s. I want to bring this up to him but don't know how. What do you think?

tl;dr bf apparently 'fell in love' with a girl he briefly met on a drunken & drug ridden night out in Ibiza (one month before we met), they didn't do anything physical but a group of them went skinny dipping (he may have had boxers on still & just topless women), I always wanted him to experience this with me first so am jealous, can't get over the fact that he did this just before we'd met as it sounds like something to be kept for early 20s, he remembered her name, occupation, height and appearance the day after & wished he'd gotten her number, month later when his friend thought his 'lady' (me) could've been her he said she was lovely but one of those you leave in a time and place, not sure if he wanted fun with her or something longer term & want to ask him.