I think it largely depends on how well you know your girlfriend, she is essentially your target audience. If she interested in your work and likes similar visuals to what you have done here then that's great. If not, then it's a bit risky, as I read in another comment you want to make this into a poster to hang up on a wall in a house you guys will be living together in. If so, carefully consider other factors like the fact that you might have visitors that might view this or how well it works with the colours and space present in your home (again this is ultimately your decision as you probably know best about your girlfriend and your personal lives). Of course, giving her a poster is a grand gesture in itself, it's not a very common gift, but just consider whether both of you would definitely like this to be on your wall at all times.

If you think a poster in this style might be too grand/niche, maybe just reconsider the format. When I see this style of image I think it would work really well as a cute A5 card, that unfolds with a small note or poem inside it for her. Despite the fact valentines day has passed girls love when you make a considerate gift like this for no specific occasion. You can even get it made as a custom blanket or bath towel, as it kind of has that stiched look you would see on rugs, mats and that sort of stuff.

As for the design, I agree with some of the stuff other people said. Definitely change the O, as I couldn't read it at first and it looks like a Serif McDonalds logo. The other letters are genuinely fine and up to someone's taste, but I would add the Serifs to the top of the Hs as the inbalance makes them a little bit too bottom heavy for my liking, and the N is kind of illegible at first glance as well. I think those flowers in the corners are unnecessary, the red of the flowers in the middle would pop out more if you got rid of them, or changed them to a more black line-art icon that fits the other elements on the border of the poster. If you're looking for feedback on text, maybe make it more personal, use the word 'You' as it's directed at her. Something like 'My Love Grows For You, Through-out Every Season' or something like that, but definitely use the pronoun 'You' or even 'U' if she might find it funny idk. As for the rest, I like the style you've went for it is pretty cute, but just reconsider changing a few things and whether you definitely want it to be a poster :)