Normally, maiko don’t have boyfriends because their life is too busy to have one and generally they do not have romantic affairs with their clients either, even though some people think they do (however when this does happen, usually the maiko/geiko retires from the profession to get married)
Both maiko and geiko can have a Danna, but it’s a rare thing nowadays because not many people are financially stable enough to support the expenses of maiko/geiko’s career - danna should be able to pay for their lessons, ozashiki, clothes or accessories and such. I hope this answers your question :)