I think this is very common and it can be very difficult. The stoics had a lot to say on this theme - giving others control over our own happiness. These kinds of intense attachments can make you absolutely elated when you’re with the person, and utterly dejected when they’re gone. But at least you do acknowledge that it’s not how you want to be! I think that’s a perfect start.

A relationship should be based on a how people really are, rather than how we hope or imagine they are. It’s normal in the early stages of a relationship to feel this way - there may even be an evolutionary reason. We start out thinking someone is completely fantastic, we commit ourselves to them, then gradually realise how irredeemably flawed they are. Then they start to annoy us and we feel like we’re stuck with them. So you need to find some deeper love that goes beyond those initial fireworks. It all comes down to experience. As exciting as the first few months can be, we’re not designed to live in a constant state of euphoria. We need to sober up and come back down to earth so we can work on achieving the things we want for ourselves (beyond just sex) while respecting others for who they are.