Me [22 F] with my boyfriend [23 M] of 5 years. How do you overcome compatibility issues? Or how do you move on from a 5+ year relationship that's all you've ever known?

My boyfriend (let's call him L) and I have been together since we were 17; we're in our early 20s now. This relationship is pretty much all I've ever known. We love each other very much; we've been through everything together and have come through a long-distance relationship (during college) to living together now.

We've been arguing a lot lately; he does a lot of things that irritate me and from my perspective, hasn't been considerate of my feelings when he does things. For example, he likes to get drunk with his friends, and I really don't enjoy that, nor do I enjoy when he does it. But this weekend we went out with one of his friends who was visiting, and L got belligerently drunk to the point of yelling at people on the street and his friend having to essentially babysit him until 5am until they went to sleep. This was the first time I felt like L was being someone I generally wouldn't associate with. He apologized later but it felt like I had to coax it out of him and he didn't mean it.

Another example: most of his friends are girls and he hasn't always been the best at establishing boundaries, so I have some residual jealousy and insecurity issues. He's much better at boundaries now, so that's not an issue. I should also mention that I have anxiety. Today while I was at work (he has Mondays off) he drove 45 minutes away with a female friend of his for brunch and then they went swimming. During the day he told me where he was, but not why or who he was with. He didn't tell me the full story until 5 hours later when I pushed him to tell me what he did/who he was with. It triggered my anxiety and I feel like this wouldn't have been an issue if he had been upfront with me. Am I overreacting?

Today he brought up that he doesn't know if we're as compatible as we were before, which might be true or it might be that we both need to put more effort into the relationship.

Is it possible to work through an issue like this and come out stronger? Is it possible for 2 people who aren't 100% compatible, but love each other very much anyway, to have a happy and healthy and fulfilling relationship? Or is the best option just to break up? How do you move on from a 5+ year relationship when it's all you've ever known? How do you move past the fear of being single? I don't know what to do.

tl;dr: My boyfriend and I aren't sure after 5+ years of being together if we are as compatible as we thought we were. Unsure if this is fixable or if we should break up. Also unsure how to move on from a breakup if that happens.