Why don't they like me?

Over the past few years I've gone from having a few good friends and associates in school to having almost no friends to speak of. My old friends are generally cordial to my face but often laugh and mock me behind my back; sometimes they even play jokey pranks on me. Usually it's fairly lighthearted but sometimes it becomes really annoying and persistent, despite them being fairly friendly to me in person they basically don't like me at all and regard me as a joke, taking the piss constantly.

It's true I have undergone some changes recently. Over the past couple of years I've found myself more strongly attracted to girls two or three years younger than me (so in this year's Year 10 and 11) and I have a girlfriend who's three years younger than me just starting Year 10. I am in Year 13. I find this to be the main source of abuse towards me with people regarding me as a paedophile etc. but really I'm genuinely more attracted to younger women!

Also, I like to act with dignity and class and I feel this has been perceived as snobbery by others. For example, I've denounced people who shop at low-cost retail chains in recent years, often use complex vocabulary on social media and like speaking French more than English despite being a native English speaker.

This is mostly because I'm insecure; I feel I reinvented myself around Year 10 to seem more 'cool' to others but I may have gone to far... this has since spiralled out of control to the current situation where I am a constant object of mockery and contempt.

The above self psychoanalysis wasn't easy to perform, but I did it for a reason. Basically I'd just like some feedback on whether you think the situation is my fault or others' intolerance manifesting... and what can I do to fix this!?