I don’t think Farage cares that much about the EU, he only cares about the money he’s raking in. He rakes in the EU subsidies by the boatload, even going as far as joining forces with extremely dodgy people only to open up more pots of money from Brussels. If he cared that much about the EU he would show up for work more regularly, you know, representing the interest of his voters.
There is some speculation that he fears a Tory majority because that might mean a referendum. The referendum will most likely be in favour of staying in the EU (ironically support for EU membership is at its highest for 23 years, https://www.ipsos-mori.com/researchpublications/researcharchive/3463/Support-for-EU-membership-highest-for-23-years-even-as-UKIP-rises-in-the-polls.aspx) which will spell the end of his party.
His problem is that most people don’t care about the EU. Ask the British people what their top five priorities are that Westminster should solve and the EU will rarely feature in it. For many it probably won’t even make the top 10. Things such as education, health care, better paying jobs, affordable housing etc. are staples of the top five, membership of the EU is not. Farage discovered this of course, which is why he had to pivot his whole campaign towards something some people _can_ get worked up about, forun people.
But yes, no doubt he’ll try to spin this as some evil plot to harm British interests. And no doubt some people will fall for it, again.