fiji boyfriend wanting to visit UK

Hello I am new to this forum and desperate for advice. I was born here in the UK and I have a boyfriend who I met over 3 years ago and he is from Fiji. I am desperate for him to come and visit me in the UK however I am worried his visa will be refused as even though I have enough money to sponsor him and can provide accommodation he has no financial ties in Fiji so am worried he will just get refused as fiji is also a fairly poor country. He has a job in a resort yasawa islands but earns little money so he hasn't got much or if any savings able. We also plam to get married in the future in fiji but I wanted him to visit the rest of my family and England before doing so. This was another thing I am worried about is it possible that he will also be rejected the spouse visa in the future. I would be very grateful for your feedback and any help you could provide.
Thanks Jo