I think this is pretty common with guys. I definitely don't think it's you.
I know sometimes doing oral on my hubby, I'll get a bit cotton-mouthed and have to stop, roll over on the bed, step over the dogs and find my water bottle, drink, step back over dogs, roll back on the bed and we're back to square one, i.e., not the erection he had when I rolled over. All of this takes about 10 seconds. Personally, I like the challenge
Something I've found with at least my guy, sometimes folks like a little variety during sex. It wasn't this way when I first met my hubby, but now after 15 years, in a two-hour span, we'll have massages, oral, penetration, more oral, more penetration, maybe some fuzzy handcuffs or bouncing on an exercise ball. Definitely keeps things interesting!
Best of Luck