Sitting in the window of a café in east London,????? ????? ??? ??? ???? ???????? I watched a lost-looking woman talking on the phone. On the other side of the glass, her two friends stood beside me. "Look to your right! We're behind you," yelled one, and peals of laughter ensued. The bewildered friend bobbed her head around, looking literally everywhere but at her tickled pals. Eventually she turned, and all three of them burst into laughter.

I couldn't help but chuckle too. But as I barely concealed my smile, I felt tears welling in my eyes. They reminded me of my own friend. With that realisation came a pang of longing that I'd been trying to suppress. I missed her.

She was a big part of my life. Until one day she was not.

I felt my friend pulling away from me long before it actually happened. It was imperceptible at first, just the odd unanswered text. She was newly in love and I was excited for her. I tried to convince myself that it was just a temporary glitch, that she'll be back. Slowly but surely, as summer faded and the leaves turned brown, the phone calls dried up. Texts sat without reply. Our meet-ups ceased to exist.

For a long time, my mind raked over things I might have said or done to upset my friend. I overthought everything I'd done throughout the preceding months. I dwelt on my own most negative traits and convinced myself of the plausibility of this theory: that my friend had just cause to cut me out.

I might've been able to mitigate the chasmic sense of loss I felt had two of my other friends not also distanced themselves after finding love. But the void left by these three close friends was significant. My social calendar emptied. My weekends became utterly devoid of brunch or drinks plans. I spent a lot of time on my own.

A few weeks ago, I couldn't bear the weight of the sadness any longer. I stood in the street outside my office building and voice-noted a friend. "It's just really fucking lonely," I whispered into my phone, blinking back unexpected tears. I'd kept my loneliness to myself like a closely guarded secret. It was a relief to say it out loud.

But, as to what I should do about it, I was none the wiser. My friend provided words of comfort, that she knew what it felt like, but that it's also natural, that we're at the point in our lives when we're all "forming units" of our own. But I wasn't doing that. Instead, my friendship units were crumbling. I had served my purpose in their lives and my presence was no longer required.

I couldn't find much online about this quite specific friendship issue on the internet, so I decided to research the topic to find ways to ease the pain for others going through the same thing.

Know that it's not personal. It's actually human nature.

The first thing I learned was this: it's nothing personal. Kate Leaver, author of The Friendship Cure, told me, "Romantic love has a way of making people temporarily (or sometimes permanently) neglect and forget their mates."

"It's just the way we've been programmed, really; to think of that sort of love as superior and therefore extremely important," said Leaver. "According to some lovely research done by Oxford university evolutionary psychologist Robin Dunbar, we lose an average of two friends every time we get into a new relationship. Oof, it's a rough statistic."

I asked Dunbar, the author of the study and the aforementioned "rough statistic", why people pull away from their friends when they're in love. "The issue is simply time," he said. "People become so focussed on the new romantic interest and devote so much time to them that they don't have as much time for all their old close friends."

"It's not so much that they don't give them any time at all as that they give them less, so they get bumped down from the category of being intimate friends to the category of good friends," Dunbar added.

In short, it's a question of changing priorities. But where does that leave you?

Invest in other friendships

While your friend is off on cloud nine, you should spend time with other friends who treat you like you're a priority, not just an option. Keah Brown, author of The Pretty One, told me one of her best friends since high school drifted away from her after falling in love. Her friend went from hanging out with her every week to no longer texting or wanting to hang out.

"At first, I was angry and then sad but now I genuinely wish her the best and appreciate our friendship for what it was and what it is now," said Brown. "But I initially felt like I was not good enough for her to stick around before coming to the realisation that the change in our friendship wasn’t about me. It’s just what happens when some people can’t juggle both." Brown made peace with the change in her friendship by spending time with other friends and "reminding myself that she wasn’t the only one I had."

Leaver also advised hanging out with friends who might have more time to give to you. "While you're waiting for your mate to start paying you attention again, it's a good time to reconnect with other friends," she said. "See your single friends or spend time with people who've been in love long enough to know they still need their friends around."

Hot tip for couples: you might need your friends if your relationship doesn't work out. Just sayin'.

Be patient and persistent

While we might want our friends to be cognisant of how their actions are affecting us, making them feel guilty might not be the most effective way of restoring the friendship to its former glory. Leaver suggested patience and persistence for the friend coping with being forgotten.

"I think we can afford to give our new love birds a short period in which they forget us, in favour of going on dates and staring into one another's eyes all the time," she said. "You can forgive your friend for having a little time to be besotted and think of nothing else; it's part of the loveliness of love."

But if, after a few weeks, they're still not returning your texts or making room for you in their life, it might be time to act.

"I think you can be very open about it and say, listen, babe, you've had your time to get totally preoccupied with love, may I remind you that I exist and I require your attention?" advised Leaver. "You don't perhaps need to go as far as saying 'who is going to be there for you when you break up with this person?' but it is entirely acceptable and in fact sensible to say 'I would like to see you' and insist on taking up space in that person's life."

Two things can be true at once: I want my friend to be happy and in love. I don't want my friend to leave my life. However you choose to cope with your friend distancing themselves from you, know that it's nothing personal.

A dear friend of mine passed on some wise words regarding this particular friendship predicament: "Eventually they come back to you." I'll be there for my friend when she does.