I feel deeply torn about my 4-year relationship, which has a seemingly insurmountable issue, especially with a proposal anticipated in the coming years.

I'm really struggling with this situation. My partner (29M) and I have been together for nearly four years, and while she's always excitedly showing me rings and discussing wedding venues, I can’t shake the feeling that our intimacy has significantly dwindled since the honeymoon phase. I'm aware that these phases are temporary, but I've never felt such a stark contrast before. It’s like I'm with a completely different person now. Flirting used to be a big part of our relationship—she would initiate at any chance, regardless of the circumstances. Now, though, that seems like a distant memory. Despite my efforts to communicate my feelings and concerns over the past few years, nothing has really changed for the better. The closest we come to intimacy now feels forced, mostly when she senses that something’s bothering me but isn't sure what. What makes it so challenging is that I'm still very much in love with her. We have a great connection in pretty much every other aspect of our relationship. We laugh a lot, have lived together for two years, and we resolve arguments swiftly. We respect and support each other in our personal and professional lives. In many ways, our relationship is healthy and functional. She has a demanding job that has taken a toll on her mental health, disrupting the balance that allowed her to focus on fitness and self-image. It's clear that work has changed her, and she doesn't seem like the same person I fell in love with, although I still find her incredibly beautiful. After two years of feeling this way, I'm reaching out because I can feel the negative impact this situation is having on me, and I don’t want it to tarnish what we've built together. I used to approach our relationship with selflessness, going out of my way, but lately, I’ve started feeling resentful about my efforts. I work hard to provide for us, plan surprise outings, handle household chores, and bring home little gifts. I listen and strive to be a supportive partner. I promised myself I wouldn’t fall into the typical traps that guys sometimes do, but now I feel like it's all one-sided. Sometimes, I catch myself thinking about her challenges to remind myself that it’s not all about me, but I can't help feeling used when my needs seem overlooked. I find myself frustrated when I receive attention from other women because I wish I could get that same attention from her. The thought of leaving feels like a huge mistake, but I can't keep sacrificing my mental well-being for the sake of what I thought was a perfect relationship. Or am I being unreasonable? I don’t know. TL;DR: I feel unable to ask for advice without providing important context about my situation. Sorry for the length.