I feel he is hiding things from me...

I wanted to surprise my boyfriend on his birthday and decided to visit him with a cake. When I turned up at his house, his parents told me he had gone for a trip with his friends. This was a surprise to me because he hadn’t mentioned anything about it to me. I messaged him on WhatsApp asking about this holiday and he said it was a sudden decision which is why he couldn’t tell me about it. I asked him why he didn’t message after leaving either and he said he just didn’t have the time. I don’t buy either of his explanations but have accepted them because it was his birthday and I didn’t want to start an argument. I have been suspicious of him since that day though, because it feels as if he doesn’t trust me or is keeping something from me. What should I do?
You can tell him how you feel, obviously, because you have a right to. He hasn’t given you any other reasons to doubt him, or make you feel as if he isn’t being open enough, so try giving him the benefit of doubt if he can give you a better explanation. It can take time for people in any relationship to start trusting each other completely, and his reasons for not saying anything may be completely rational from his perspective. Take your time, allow communication to evolve between you two, and look at how things have changed a few weeks down the line. If you still find things suspicious, talk to him about it again, until that feeling goes away. If it doesn’t, the two of you may have a problem.

My girlfriend repeatedly makes a mess in my room whenever she is over, which I think shows a lack of respect for my personal space. She thinks I’m being too picky and should accept her as she is. Is she right?
No. Your personal space is yours, and you alone can define how it should be treated.