What is love?

I don't think age really factors into it.

Perhaps in teens and early 20s, priorities are different. You might even be in university, have a long term relationship where neither of you have fully thought about the future. Perhaps a first love. Then you realise that you both want different things, but are not prepared to come to a mutual compromise. Then, it wasn't really love. It was infatuation, and a companion that suited that time of your life, but real love involves compromises and would survive all that.

Yet, years later, you compare your first love to every other relationship you've had and still claim that the first was the best. Why? Because you were both young, had different priorities and everything that goes with not yet living out in the big bad real world.

When you're older, you have different priorities, responsibilities, work, bills and so on. You still have fun and enjoy time together, but it's definitely different. You can still have that "wow" feeling about someone, but I also think it's important to recognise that oftentimes that "wow" you're feeling is just infatuation and it kinda fades after the first few months.

Romance movies paint this stupid picture of how it's supposed to be. But In real life, love is basically having a best friend that you feel that you can share everything with. You might get on each other's nerves from time to time, but...you always work it out. You don't try to change the other person and love them for who they are. A friend once said to me "I found the love of my life, someone who puts up with all of my bullshit, and I put up with all of hers." I thought that was a good way of describing it. If you like this new girl, give it a chance and see where it goes. =)

Personally, I haven't found that yet, but... giving up is for plebs. XD.

https://www.youtube.com/watch?v=dEy3xJvozq8

It really is good (usually great) in the beginning, which personally makes the other stuff worth it for me (save for maybe that one girl I never talk about anymore).

Then it becomes a balancing act requiring a lot of patience, understanding, grace, and maybe a bit of sacrifice, which only works if the other party reciprocates.
I'd like to think I've had mostly successful relationship (at least in the sense that we can still communicate after the breakup, occasionally say hi, and wouldn't have to avoid each other if we run into each other someplace).

Never think of changing something for someone as "settling", but be mindful how the other person responds towards your needs and how they adapt to it.

The best (and lengthiest) relationships I've been in involve both parties choosing to nurture each other rather than living without

It's a platformer :
https://store.steampowered.com/app/269270/LOVE/

Another answer.
https://www.youtube.com/watch?v=HybcK892uBY

Don't give up. If they're worth the effort then give it a shot.

just to share another point of view: https://acutelesbian.tumblr.com/post/132084506833/fat-thin-skinny-acutelesbian-a-lot-of-people

I might come late to the talk, but:
Age doesn't play a role. I've seen it, and I experienced it myself. You might get more experience, more disappointment, less motivation, better insight, some wisdom (with luck!) and other things... You doubt it exists, you think you're not up for it anymore, and start to think things like those - most ppl of my age have someone else, I am not how i used to be, etc. And then it happens, and you are asking yourself 'how' and 'why' and 'what'. I was years (decades) trying to find that... I surrendered, thinking it didn't exist (anymore). But it did. So, don't surrender, don't despair, if that's something you want and need in your life, keep searching for it. It doesn't need to be an epic love story like the world hasn't ever seen under the sun. It just needs to be important for you, and then it'll be important. Good luck.

https://www.youtube.com/watch?v=fHKVETEnB34

Throwing in my opinion...and this is only based on my own limited life experience....
...I don't think feeling smitten is only a young person's thing, but it's less common as you get older. As you mature, you know yourself a lot better and know what you want in life (and a partner) so it's more difficult to find someone who evokes those feelings. Also, if you spend a lot of your life alone, you get used to being on your own and (most people) are comfortable spending time alone. This makes it more difficult to fit someone else, with their own habits and annoyances, into your existing routine. I found when I was younger, I'd fall for someone very quickly then after a couple of months when I got to know the real person I was less interested. Now I'm more aware of that and try to be more wary and control my feelings. Basically, I've got pickier!

"On one hand waiting for that special feeling you had back then, but might never come anymore, or on the other hand fall in a trap of you are single, i am single why not try it out for the sake of it?"

That's a difficult choice. If you 'try it out' are you going to get hurt? is the other person going to get hurt? are you going to get stuck in a relationship that you don't want to be in?
I don't have the answers, as I'm of a similar age and single myself! :)
I can only share my own thinking on the topic.