It can work out but you said yourself that you are not feeling it. Don't feel guilty just be honest with yourself and him.
most of the things u listed that made your relationship seem weird and challenged arent related to "age difference, culture difference, or language barrier". they're just related to who u are and who he is. i mean theres no culture in which telling your gf to keep their old engagement ring *with someone else* for a potential future use is okay. my lovah is british and im french. i speak english fluently so we dont have trouble understanding each other, and i dont stay with him so he can teach me english, even if its nice that he does without being aware of it. he doesnt need to learn how to speak french cuz theres no misunderstandings due to language between us. but in your case i would suggest u try to learn his language. as for the age difference i have a 6 year age difference with my lovah. so yea i understand some of the stuff u said, but im pretty childish myself so i never really think of the age difference. i only think of it when my bday is coming up actually lol. 6 years isnt much, maybe u're a bit more on the wild side at age 21, but its not *that* different to when u're 27. u're both in your 20ies, u still have a lot in common.
You don't seem like you are all that into the guy, so I'd move on. The issues you are having aren't due to his culture, not the deeper things like the engagement ring sonareo, and I don't understand how you can talk for ages when you first get together and it appears not to so much now? I honestly think, if you aren't happy with the guy, then tell him.
You seem like searching for reasons and people support to end this relation.., either you feel emotionally happy with him or not..you talk as if you are judging a third person or completly with mind filled with objections from some people who are against the idea. If you are not at least 80% happy with the emotional side of this relation..do your self and him a favor and end it. But if you like to be involved then here it is: 1. Six years older is not much of a difference, and if he 21 then you are 27 which is very very young. 2. For him to learn English or to get to know American girl..sure not. He can do that in his own country or by going to a bar or something like that..and he is staying in USA, so learning English is no trouble, and does not need you for that. Because most of what he is going to meet in America are people who speak English. The thing to watch is: if he in it because of a Visa or something similar..If not..then you have no problem at all...if yes and you are sure he likes you then why not ?..you will be able to study him when he settles in USA and before any serious decision by you. 3. When he mentioned the woman older than him..guess that his intention is to assure you that age is not a major issue, just like many other people. Older than him with 14 or 20 years relation this happens every day all over the world. No fetish is there. Lol. My first Sex experience was with a woman of 45 or 50 years. So till now, find no problem having relations with older women..what is so strange about that ? they might not have the perfect body they used to have in their 20TH but know how to please a man Pysically and Emotionally..that what counts. 4.The Ring thing..is not very clear...maybe you should ask him what he means. 5. Dictionaries in 2 countries..of course differ..it could be very well i want to make some one happy with the way i learned and know in my country, yet only to mange to make that person angry according to his/her dictionary...time will make that better. Summary: Now you will have more time to study his integrity with you...And your feelings to him.. Give it some more time..and see. also Yes totally different cultured marriage work well specially if there are common things going.. and some comprimise. Give it some time..watch and analyze...then decide. Meanwhile why do not you enjoy it..the man is quite open to you and telling you what's in his mind. Lanugage Barrier will be down soon, Age difference is of no significance difference here, i.e. too little, Cultural differences...what cultural..the only thing that can relate to your realtion is if he wants a faithfull girl and you do not believe in that. It seems after 2 marriages..there is part in you that hesitates...as you spoke very rationally..try to judge him rationally and fairly too.
So what's with the Judgement thing you got going on with him being with a Woman older in the past? Why would he feel that relationship was wrong? Sounds like your coming from a place of looking at all his stuff but not looking at YOUR ISSUES.