I think it's because of the recent development that Ripple is doing, the xRapid and xCurrent, but don't lose hope because Ethereum is also trying have it's better version (Link) and maybe that's the catalyst for eth to regain it's throne. Overall, market is on bad condition so maybe that's the result and with Ripples continues updates this bear market, maybe that's the reason it stays on the top two and might last longer if ethereum didn't have it's catalyst to go back up.