Do I stop seeing this guy? How do I make sex better? *HELP*

So I lost my virginity to one of my sisters close friends and no ones knows we’ve been sorta seeing each other for the last couple months. At first I just wanted to get some experience sexually with someone I was comfortable around but he came on really strong and admitted all these feelings for me and now I really like him but he’s acting different and i don’t know what to do. He never seems that concerned about making me cum and the sex ain’t all that but I’m not sure whether that’s because we’re still learning what each other likes. The last week or two he’s been acting weird and when I’ve brought it up he reassures me that’s it’s not me and is all lovely but I can’t help but think I’m wasting my time. Like the sex ain’t all that, he’s always satisfied and I’m not, seeing me seems like a chore and he’s terrified of my sister finding out even though he really wanted to tell her at the start but now is acting funny. I’m struggling to decide whether to end it cos I like him so much and I’ve never felt like this about someone. I really don’t know what to do