Hi everyone

About three weeks ago I moved flats and am now am sharing with someone I met through an advert. She's pleasant enough (we don't have enough in common to ever be best friends but she's pleasant enough to live with) but a couple of things her boyfriend's done have pissed me off a bit and I'd like some advice on if I'm being massively petty and should just learn to be more accepting or if these are reasonable issues for me to bring up with my flatmate and hopefully discuss as adults but maybe risk bad feeling.

The two issues are

a) It's a small flat and sound travels quite a lot. He sits in the lounge playing the guitar really loudly in a way that I suspect is intended to wow any one listening with his technical skills but is actually pretty annoying and just cuts through anything I'm trying to do in my room that doesn't involve listening to really loud music. I kind of want to ask his girlfriend to ask him to close the lounge door when he does it (I tried this once and it worked for about five minutes ) or do it in her room so I don't have to hear it.

b) him still being in the flat after she's gone to work and letting himself out later. I kind of feel if my flatmate isn't there there's no reason her boyfriend should be either.

I'm aware that I've got a bit of a complex in that I find it really hard to relax if someone's in my home that I don't really know and so this could easily be clouding my judgement so I'd really appreciate some advice on whether either of these are actual issues it's reasonable for me to raise or just quirks to be accepted about living with a stranger?