Feeling stuck…

I’ve had a relationship with my partner 4 years now. Time has passed and stress of life and work along with it has changed our dynamic drastically. On off days (we don’t get many due to jobs) we argue and find issues to have on the days we’re by ourselves. In conversations we’ve had about solving these issues despite whoever’s at fault and solution we came up, no change happens. We speak on two different love languages in a way that has made me feel I’m not enough or I don’t do enough for her to be happy in the relationship. Most of the issues come from money, being for groceries or activities that she would like to do, so I work myself harder to try and accommodate but then it’s an issue of I’m not home enough. She wants to be engaged and married to me and in my head she’s the only one I see it happening with but with the constant doubts on whether I love her or not (something she actually brought up to me at a point in one of our conversations) and the constant question on whether what am I giving for us is good enough is hurting me. While I love her, I just can’t see marriage anytime soon and I worry that answer will upset her in some shape. I’ve also found myself growing close to a work associate, who makes me feel better and brings me up but also in the same sentence she throws me to the side a lot because she has a fiancé and has expressed we can’t do whatever it is we do but comes to me in her times of need and lays on me at work on break and as awful as it is it brings me peace. I just feel stuck with the amount going on and this pit of depression I feel I keep falling deeper and deeper too has just transformed to me losing weight, taking recreational drugs a little too much to be able to not feel anything or make myself think or dwell to much on the matter along with on and off alcohol stints I go through. Sorry if this isn’t okay to post, I’ve never done this. Before and figured I coldly try