Depression and relationships!

I have depression, or what is undiagnosed depression and I've had it for the last 6 months.
My relationship has suffered greatly because of this, and I feel a terrible "doomed" feeling whenever I think about us. I really love this guy and I'm very attracted to him... Honestly I look at him and feel sad almost as though he's not mine? When he is, obviously.
I'm here just for anyone elses experience with depression and how its affected your relationship?? Feel like I'm the only one going through this.