Oh god, just go! My DP and I have a lot of music taste in common, but mine is definitely wider / more eclectic. For gigs at our local venue, if he, or none of my mates fancy it, I've gone on my own. It's a friendly venue and I either see people I know, or make new friends for the night.
Then last year, an obscure, but amazing band* I love were coming to the UK, playing in London. I bit the bullet and bought a ticket, got the train to London and saw them play. It was really liberating and I'd definitely do it again. I'm 46F.
I see you said it's Enter Shikari, I saw them support The Prodigy in 2010. If you are worried about being alone, see if anyone on their Facebook group is arranging pre-gig drinks at a pub nearby, or suggest it yourself.
*The band I went to London for was Mongolian throat-singing metallers The Hu. 🤘🏻 They were awesome.