Where to go on holiday for around 2 weeks with boyfriend? (17 + 18 y/o)

My boyfriend (18) and I (17) are looking for a destination in the Pacific Islands to escape to for a holiday.
We want a holiday that is fun with plenty of activities on offer based around water and sight seeing probably, as with any holiday, and also with some romance to it also, which I presume we could find on most islands?
Nothing too built up with cities and an english speaking country is preferred.
We want the beaches, the sun, the peaceful pacific paradise, with plenty of fun activities.
Our budget will be rather small considering our age, but still healthy. Nothing too fancy though.
We are looking to go for around 2 weeks and also need to look at planning an itinerary and a budget.
We have plenty of time before our holiday for extra saving so we have time for planning to ensure an unforgettable holiday with our money well spent.

Please, can you give me some suggestions on where to go? And also some activities to include in my itinerary?

Your help is much appreciated!!
Heva :)

Since you're young, you probably would want somewhere relatively inexpensive and easygoing for 'new' travellers, so I'd suggest Fiji. Fijian's English skills are usually good - definitely better than Samoan's.
Look into the Yasawa and/or Mamanuca Islands, or elsewhere that's off of the mainland (Viti Levu). Plenty of snorkelling, diving, beach-bumming, hiking, village visits, kayaking, and so forth to keep you busy.

Thanks, I did have Fiji in mind. I will definitely look further into it, thanks so much for your suggestion!

Since you are going away for 2 weeks maybe you would get bored if you stayed on just one island in Fiji. If not the best option for young people is Beachcomber Island - a real party island! The other option is North Queensland (maybe just not right now cos of flooding!) The Whitsundays all the way up to Port Douglas is pretty cool.

Have a look at Ha'apai in Tonga. It just might be your thing.