Sex not lasting :(

My boyfriend and I have been together for about a year now. Love him to death, and will marry this man but our sex like kind of sucks at times. He always makes sure I’m good but sex only last 3 minutes and I think he feels bad bc I don’t crave sex like he does bc there’s not much to crave. We tried condoms, and new positions but I’m just not excited to have sex anymore bc I don’t feel good.