when his explanation includes the following behaviour on receiving Marianne's notes.

Well first he fans his ego a bit;

"Marianne's note, by assuring me that I was still as dear to her as in former days -- that in spite of the many, many weeks we had been separated, she was as constant in her own feelings and as full of faith in the constancy of mine as ever.."

Now his response to the notes;

I sent no answer to Marianne, intending by that means to preserve myself from her farther notice; and for some time I was even determined not to call in Berkeley Street: but at last, judging it wiser to affect the air of a cool, common acquaintance than anything else,..

Now comes the fun part. Imagine Willoughby hiding behind a pillar or something, sticking out his neck every now and then.

I watched you all safely out of the house one morning, and left my name."

He did this quite often it seems.

You would be surprised to hear how often I watched you, how often I was on the point of falling in with you.

But contrary as ever;

I have entered many a shop to avoid your sight, as the carriage drove by.

Here I picture him running into the nearest shop, be it a woman's dress shop, much to the amazement of the customers and the shopkeeper.

Lodging as I did in Bond Street, there was hardly a day in which I did not catch a glimpse of one or other of you;

Hmmm. Like stealthily pulling the window curtain aside, just a wee bit, to peep out.
He did it quite tenaciously it would seem.

"...and nothing but the most constant watchfulness on my side, a most invariably prevailing desire to keep out of your sight, could have separated us so long.

He forgot to add - and how proud I am of my (continued) endeavours.

I avoided the Middletons as much as possible, as well as everybody else who was likely to prove an acquaintance in common. Not aware of their being in town, however, I blundered on Sir John.....,

awwwww!

Some more much deserved ego fanning, after all the dodging, and hiding, is now in order.

The next morning brought another short note from Marianne -- still affectionate, ..

And yet;

I could not answer it. I tried, but could not frame a sentence. But I thought of her, I believe, every moment of the day. If you can pity me, Miss Dashwood, pity my situation as it was then.

His situation!!!
The only one in my mind is the one behind pillars or curtains.

And then - *bang*

you were forced on me:

and

I ran away from you all as soon as I could,
Bravo!!!

But wait!!!

...not before I had seen Marianne's sweet face as white as death. That was the last, last look I ever had of her; -- the last manner in which she appeared to me. It was a horrid sight! Yet when I thought of her to-day as really dying, it was a kind of comfort to me to imagine that I knew exactly how she would appear to those who saw her last in this world. She was before me, constantly before me, as I travelled, in the same look and hue."