I'm going to write this critique as I read through it (not for the first time), so the only order any favouritism (ie. I like this part because of...) or critique is, is due to what I think of the stanzas in their current order. That aside...

The word petite; I wouldn't necessarily substitute it for something else (ie. small...) because it's not a matter of needing another word for it in order to fit. I think it's because the word is so often underused, particularly when describing any element of nature. But with that said, rather than using a different word, the line would work just as well if it wasn't there; it's not often needed to describe the length of grass, perhaps unless it's tiger-grass which grows to ridiculous heights.

...a late sunset's alcove is striking imagery. The comma after 'hope' is a hit-or-miss with me (if you read the last two lines of the first stanza as just a sentence, you can still either choose to use the comma depending on whether you want a deliberate pause or not). I'd also remove the comma after 'laid' (the first line) and the period after 'alcove' (replace it with a comma).

In summer's height, unless it actually is a referral to more than just the one (over a course of years...). I'd take away the period at the end of 'advances' because as it is now it seems to be rather abrupt and jars the rest of the stanza (which is also how I feel about the period after 'alcove').

Rufescent should be relucent (meaning: bright; shining).

Even though I've advised (please always remember that, at the end of the day, this is your work and it's up to you what you choose to revise, regardless of who is saying what) that you take away the periods from the end of the second lines of the first two stanzas, I feel that it works well on the third stanza.

I feel, that although this is going in seasonal order, we're really viewing it over a course of three separate years with Autumn being the first (Summer being the second; Spring the third...); at least, that's what the 'On one knee I met you in autumn' line slots into place for me. It's quite a good effect, even if it isn't intended. Despite that, I feel that Winter still fits nicely on the end...

The word fastigiate refers to trees or shrubs, and means to have the branches sloping upward, or else parallel to the trunk. I don't presume that it's meant to be taken quite so literally, but I feel that it is in need of substitution (if not for another word, then perhaps for 'And we could only keep moving).

As a matter of explaining why I gave you the star ratings I did:

Vision: I don't intend to compare whoever I'm critiquing with anyone else, and if ever there is a comparison it will be between your own work (ie. 'you don't quite achieve the effect here that you did with so-and-so, etc). Hence the five stars for vision: we're not devoid of imagery, and each description works very well in portraying the atmosphere and the circumstances. It's quite lovely to read through largely because of this.

Originality: Like with vision I don't intend to compare you personally, but generally romance and love poetry is far and wide - I dare say it makes up the majority of poetry, both on dA and elsewhere (that 'outside' world place...). That's why I'm instead judging based on the narrator's interpretation and description of their love/romance, rather than just on the love/romance genre, and as I said previously, it's successful.

Technique: I'm certain that all that needs to be explained has already been said above, but to summarise: good description, fairly well done execution, and the imagery is grand.

Impact: If one wanted to melt a cynic's head heart, I'd be surprised if they couldn't at least admire the (yet again) imagery.