Teenage daughter, should I be worried?

[Jduvtr]

First of all sorry about the username it’s impossible to find a valid one. I have a daughter 16 and she has been off and in with the same 17 yr old boyfriend for 3ish years, When it is on she is a different person we don’t get in she’s moody and not a nice daughter, when off she is happy and our relationship is great. Recently I have started to look at her messages as she has been speaking to him and been moody, upset, recently even said she wants to kill herself because of him. She has blocked all boys in social media as he is horrible to her if she isn’t and has recently come off Instagram even though it is usually her life. He hasn’t though and is regularly cheating on her and when she says anything to him he flips it to her and says she is doing this and that when she isn’t she doesn’t do anything for him. I don’t know what to do, she is about to start dance college in September, a exiting new chapter in her life, do I sit back and watch him ruin it for her or do I intervene and remove all electrical devices and ensure contact stops? Please help!

What's she like if you sit down and talk to her about it?

Do you have a friend or family member she can confide in?

I've often used the idea of a fresh start with my own daughter and with students I taught. There's something really lovely about that - starting somewhere new, where nobody knows you. Of course that would only work if she shook him off at the same time. Can you talk to her about how her mood changes when she's seeing him and how relaxed and happy she seems when it's over?

Perhaps talk about a boy you dumped (or someone you know, preferably someone she likes) where you/they felt fantastic afterwards?

Or ask her to visualise a future with him in it and another without him?

Perhaps introduce her to some terms like 'gaslighting' and 'the pick-me dance' (after infidelity's been discovered) - if you talk to her as an adult she may well take things in deep down, even if that's not apparent immediately.

If they are on and I try talk to her she just denies him ever doing any wrong, he speaks to her like crap there is no romance there, she says things to me like I can do what I want and I’ll move out then. If they are off she agrees it’s no good and says she won’t get back with him but she always does he manipulates her.
Yes, I have people she can talk to but I’m not sure she would listen.

So I'm now 20, but I was in a relationship with an older guy when I was freshly 18. (granted, she is younger than I was) and I was in a very bad relationship with an older man. Your daughters bf is displaying similar behaviour to my ex and from experience if you feel you need to interfere, please do.
I resented my parents for showing concern regarding my relationship but now I'm out of it we are close than Ever. I used to be awfully moody and wouldn't talk to my family or friends and it took people telling me how unhealthy the relationship was, and how I shouldn't be that unhappy with someone who supposedly loves me, time and time again for me to realise the same thing. Trust your instinct please!

I think deep down she knows it’s no good a few her friends have recently got pregnant and I’m so scared that will happen to her and then she will be tied to him forever and her future is over. Would you let her carry on going out even if you knew she was meeting him?

Thankyou for that, I was also in a bad relationship when I had her so I feel guilty which is why even more so I don’t want it for her. If I asked her to choose our family or him I honestly think she would choose him. Don’t get me wrong he doesn’t hit her or anything yet but it’s emotional, he’s changing her from the popular happy girl she used to be and I can’t see it ending well. I feel like not letting her out my sight and taking her phone but don’t want to make it worse.