And your date doesn't make a bracha. Would it bother you? Would you say something? Would it be a deal breaker?

I would assume that I just didn't notice him make a bracha. If he washed and didn't bentch and I hadn't gotten up from the table (so I couldn't have missed it), that would be a bit off-putting. It wouldn't be a dealbreaker, though. Also, I wouldn't say anything about it.

If they generally didn't make brachose that would be a deal-breaker for me. But, if it happened just once, then it's totally possible that they forgot, remember they could be really nervous. I had one date where I completely forgot to bentch, and only remembered a day or two later. For all I know the girl thought I was really not frum, but hey we all make mistakes.

Well, I'd consider it an indication of a certain laxity in their yiddishkeit. Because I'm a little forward, I'd probably mention it in a playful sort of way, and see how they respond. I think the attitude behind it would be more of a deal-breaker than the act itself. Saying "Oh! My bad! I usually don't forget" and saying "Yeah, well, it's just a stupid brocha" would say two different things to me. And if he got extremely defensive with my asking, I'd probably wonder about his temperament in general.

I would call her rabbi after the date and report her.

I'd issue a midos alert

I'd make sure to notice if he made another bracha on something else, so that I can confirm that it's not a habit.

Say something. Just to find out why.
This is a great opportunity to be DLZ.

I would assume that they just made the brocho quietly or I missed it. If I noticed she doesn't make brochos at all it would make me question her religiosity in general. Especially on a date when she's supposed to be on "her best behavior".

People chastise me all the time for "not making Brochos" and when I tell them I most certainly did, they usually respond "I didn't hear it" to which I respond "G-d heard it, it was meant for HIM, not YOU"...

No i would not be concerned. Some people forget to make brochos, its not like they forgot that they can't drive a car on shabbos.