Why doesnt Peter trust Matt?

Other way around...Matt couldn't trust Peter because Future Peter sent him to Africa after shooting his brother...

Peter didn't trust Daphne

I don't trust her either...

o so did he say she can't be trusted...i thought he said he..she was there when arthur took his powers right?

because she was one of the people after him in the future remember

Yeah, I think she was there. Also, she kicked his ****** in the future!

Oh, I love ******-kicking girls! lol

Peter: Matt?
Matt: Peter?
Peter: She can't be trusted! (Pointing at Daphne)
Matt: You can't be trusted! (Pushes Peter to the wall)
...
..
.

Its clearly because of the future he went too.

ok thanks i heard wrong i thought peter said he

Also she was in the room when his powers were stolen from him.

Yeah, Peter was referring to Daphne. In the future, Daphne was part of the group that attacked Peter and Gabriel. You know, trying to kill Peter and setting off Gabriel exploding. Bad stuff. Peter didn't really get to know her the way Matt did though.

Good call. So Peter saw her working with Pinehearst in the present and the future both, which is why he told Matt she can't be trusted.

The real question is now, why Peter lets her hang around without even little explanation, like: "Yeah, I worked for your dad, and I'm still kind of working for him, but you'll let hang around for a little time, right Maaaatt?"
Or Matt could just have said: "It's okay she's with me", or something.
But I guess Pete has a lot on his mind lately, poor boy

What is Peter going to do to stop her? He could say something to his mom but not in front of Matt. Pressing the subject is likely to just make Matt feel irritate and suspicious of Peter.

Because there's not enough time in each episode to be arguing about those little things, unless it's essential to the plot?

Quite amusing to see Matt then try to read Peter's mind, you would of think after what happened to him when he tried to read Peter's mind he would of been a bit more reluctant to try that again!

Was it stated that it was Pineherst they were working for? In actuality, Future Peter was supposed to be the bad guy and it was Claire, Knox, and Daphne who were the good guys, at least from their point of view. Of course, I can't picture Knox as a good guy but this justified why Matt was still with Daphne (and Present Matt understood this as well). So aside from hanging out with the wrong crowd, while Daphne may be a morally gray character, she hasn't really done anything to make her a true villain.