um, I think you are extrapolating hugely here, it was one friend who only commented when OP specifically brought it up - OP doesn't say that anyone else has ever suggested she is tight or doesn't pay her way (which you think by the age of 31 someone would have mentioned if it were the case). None of the other friends who were with OP agreed with the friend, and even that friend didn't say "OMG, you save half your income and you're still scabbing off us for drinks" (or similar, which, again if OP was so tight you think would be the perfect opportunity to bring it up).
We also have no idea what that friend's own financial situation is like - they could be an absolute spendthrift who is thousands of pounds in debt, in which case I'd prefer OP's way of doing things!
OP I'm slightly older than you and do own my house, but otherwise similar circs, and just realised I probably save half of my income as well, although without really aiming to. TBH I don't find it a huge struggle - I've never been someone who likes 'stuff' so I never feel like I'm denying myself. I'm a bit of a worrier, so having the money saved is really beneficial for my mental health because it stops me from thinking 'what if.' It also means on the occasional times there is something either that I want or would make my life easier I can just get/do it without thinking or feeling guilty - e.g. it's raining and I cba to wait for the bus so get a taxi, a few years ago I took a career break to go travelling etc., To me that makes me much happier than buying a new nail polish once a week or getting a takeaway or whatever.
I also don't think my frugality negatively affects my friends/family in any way - I always cover my share at minimum, and because lots of my friends are in the small kid stage they are probably more frugal than me - if anything I'd probably be more up for going out and spaffing £40 on a bottomless brunch but we usually end up going to someone's house for a takeaway more often than not to avoid childcare costs!
I think particularly if you're single it's wise to save if you possibly can - you don't have the fallback like you do if you're in a couple, where it's unlikely that, for example, both of you would fall ill or lose your job at the same time. If you're single it's all on you.