My Dad who is 85 was diagnosed 2yrs ago with early Dementia which he has been in denial until now. He went away on a coach holiday alone and

When I collected him he was very Disorientated is this because he was not in his normal routine? Also he thinks a 40 year old columbian woman loves him (he did live in Panama) and he is sending her money monthly. I'm beside myself when I try to talk about her we end up arguing. I've said we need to visit the doctor for medication and he said he is not ready. What can I do?