Well, blossoms do not last for ever visually ! After getting pollinated they shrivel and you wont them. Then after 2 -3 days a tiny fruit should be taking form.
The other rare possibility that some insects/pests are eating them ?!

Sey

They're aren't pollinating. There's no fruit, just a stem. If it was blossom drop (which I've experienced before), I'd expect to see the failed blossoms lying in the dirt around the plant (they're in containers, btw). But I don't. Just sheered off stems and no blossom anywhere.

So, do I have a pest? And what can I do about it?

Hi Ali Khat. I get the same problem and only occasionally will see a blossom on the ground or still clinging onto one of the stems. No, it's not a pest. You may have over-fertilized, but it may simply be that conditions aren't ready yet for your plant to support fruit. Don't worry about it. Likely you will soon be swimming in yummy tomatoes!

Please do add your planting zone to future posts.

I'd say thrips but you'd still see some fallen blossoms they have nipped off. If no sign of the fallen blooms at all then I'd suspect birds taking them. It is nest building time.

Dave

Hmn, birds are a good possibility. I'd hate to put netting up around them, though. I did that once, many years ago and a blue jay got caught in it overnight and strangled before I could find it.

The weather might be a factor, too. I'm in SoCal and we had a cold snap followed by a heat wave followed by another cold snap just in the last three weeks. I'd be relieved if that's all it is and I just need to be patient.

I have never seen thrips cause blooms and fruit to drop. I have seen them cause leaves and flowers to be a bit deformed and to leave behind white, raspy marks on leaves and flowers. You can tell if you have thrips by blowing your breath on the growing points of buds and flowers and if present, they will come out of the folds and run around.

No white marks anywhere. So, it's probably not thrips. Just the blossoms being cut off mid-stem with no sign of where they went. I guess it could be birds, as digdirt2 suggested. Though, honestly, I've never seen birds go after the blooms before, just the tomatoes.

Ali Khat, I'm in So CA also, on the coast. Unless you have a variety that specifically grows in cooler conditions (two of my favorites I grow successfully in May are Oregon Spring and Siberian), it's still not consistently warm enough (even inland) for good production. Keep on keepin' on with your plants and you'll have success by July-August. Good thing about our area is that, once they are growing and fruiting, our tomatoes keep going into late October or November.

I've heard that, but in the seven years I've been raising tomatoes, I've never once gotten them to last past August. I'm in the SF Valley and the combo of heat and pests just destroys them. Ordinarily, I get tomatoes between late May to early August. It's wonderful, but it's brief.

Ah, SF Valley. Yes, much warmer!