Why do people behave this way to me?

[HoldenC]

I like to consider myself a nice person, I'm kind and thoughtful and make effort with my friends. I am however firm and not a pushover so I don't understand why people constantly push my boundaries? Few examples from the last few weeks:

1.) Things went sour with the guy I was seeing and I went off him a bit. I asked for some space to be on my own. He didn't understand and kept texting saying he didn't see why I needed space. One night he said 'fuck it I'm coming round to yours'. I had to text several times 'do NOT turn up at my house uninvited please'.

2.) The guy's mum started messaging me on fb a few weeks ago, saying she couldn't wait to meet me etc. Then she added or followed me on all my social media which is private. When I split up with the guy last week she messaged me on Facebook saying she hoped we could have worked it out as I sounded a good match for her son . I found the whole thing very odd.

3.) I've been having a stressful time lately and been trying to quietly phase out a 'friend' out who causes me nothing but hassle and stress. She is the sort of person who causes arguments and dramatic situations with literally anyone and I was done being treated like shit. I didn't want a big falling out so tried to just gradually phase out the friendship. She started ringing me 20+ times a day demanding to know why I wasn't speaking to her as much. In the end I sent her a message politely stating why and she blew up, went crazy. I had to delete and block her. Since then she's got her brother to message me on Facebook, has sent me a massive email and turned up at my house uninvited.

I'm just so fucking sick of people not respecting my boundaries and treating me like this. Are people like this with everyone? Am I just unlucky enough to have had these people in my life? It's really getting me down.