I think rushing sex that you are not comfortable with because you won't have another opportunity for a while would be a mistake. Have sex the next time he visits after you are fine with it, and not a second sooner. And if you are fine with it the day after he leaves, oh well, he'll be back if it's going to last, right?
I can't say what attracted him to you, and if it does seem suspicious, stay on your guard, but whatever you look like, remember people have different tastes. It could be that all the "pretty, young" females in Brazil seem to look better to you (and might to other people, too, which could have been your experience) but to him you're exactly what he's attracted to.
If that's the case, it's possible he saw you, thought you were his dream female, physically speaking, and wanted to approach you and not let you go.
If that's the case, he'll be fine with waiting until you're ready. If you're that special to him, he won't want to risk ruining it, as frustrated as he might get.
Either way, sex because you think you'll feel guilty if you don't seems like a terrible idea. You don't owe him sex because he finds you attractive and he's nice to you. This reminds me of insecure teenagers who have sex when they're not ready.
I don't mean to insult you here, and I'm sorry if I seemed disrespectful. You're someone who has shown good judgment in the past and a lot of maturity, and I think you realise that pressured sex is a bad idea. Just don't torture yourself over it, and be confident. If he gets upset about it he wasn't worth it in the first place. If he's really too good to be true, he'll be fine with it.
Good luck, and I hope everything is true despite being so perfect. Keep an eye out for anything fishy, but don't forget to also enjoy the good times