Is it normal my friend thinks time has no objective reality?

Time is like money, it has meaning because we give it one.

According to General Relativity time is relative to a frame of reference determined by gravity and/or acceleration, subject to the equivalence principle. What matters is chronology of events.

It depends on what your boyfriends definition of "time" is.
If he is referring to “seconds, minutes and hours” then, yes.. humans invented “time” as a standardized unit of measurement. Just like we invented other standard units to measure things, like liters, gallons, centimeters and kilometers.

Put an ice cube on your counter and watch it slowly melt. Leave the puddle of water and it will eventually evaporate. We have an example of water that went through phases of solid, liquid and finally gas.. ask him why didn’t it happen instantly? Did he “invent” the “time” it took.. or did it just happen naturally?

Time does exist – otherwise everything would happen all at once.

I feel similarly, when I'm late and need to justify it. However, the time we've constructed (e.g. Seconds and hours) are simply constructs to measure an intangible, yet real, thing.