My best friend boyfriend

3 years ago when my best friend have an trust issue with his boyfriend. That time she is mentally depressed by his behaviour. He thoughts she was cheating on him. I don't know much about her boyfriend but we talk sometime. I wanted to help her so I talk with him personally. It was my bad decision I don't know that time. I just trying to help my friend. So me and her boyfriend continuosly chatting on whatsup to resolving their issue. But that chatting gonna wrong and he started to enjoying my company and attracted towards me and one day he proposed me. I'm totally shocked I just don't know what just happened. I cried whole night that day. I don't know what to do, do I tell to her about this but later i decided to keep it this secret. Actually I don't wanna lose her at that time I have only 2 friends and one is living far and also I don't wanna break to their relationship. I just dlt him from everywhere and never contacted. I realised that it's just couple matter. After i never talked this matter to anyone except my second bff. Whenever I saw him i just blackout later I trying to comfortable because if I reacted my friend asked me what happened so I have to tell her everything. So I just started keep distance from her and his boyfriend.

This taught me big lesson of my life never and ever been indulge between couple matter. After the fight ended they were together and gonna blame you.